appl. phys. express vol.1, no.1 (2008) 011101 first ...takuma nanjo*, misaichi takeuchi1,2,...
Post on 07-Oct-2020
1 Views
Preview:
TRANSCRIPT
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.1 (2008) 011101
First Operation of AlGaN Channel High Electron Mobility TransistorsTakumaNanjo*,MisaichiTakeuchi1,2,MuneyoshiSuita,YujiAbe,ToshiyukiOishi,YasunoriTokuda,andYoshinobuAoyagi1,2
(ReceivedNovember1,2007;acceptedNovember6,2007;publishedonlineDecember28,2007)
AchannellayersubstitutionofawiderbandgapAlGaNforconven-
tionalGaNinhighelectronmobilitytransistors (HEMTs) isonepossible
methodofenhancingthebreakdownvoltageforhigherpoweropera-
tion.WiderbandgapAlGaN,however,shouldalso increasetheohmic
contactresistance.WeutilizedaSi ion implantationdopingtechnique
toachievesufficiently lowresistivesource/draincontacts,andrealized
thefirstHEMToperationwithanAlGaNchannellayer.Thisresultisvery
promising for the furtherhigherpoweroperationofhigh-frequency
HEMTs.[DOI:10.1143/APEX.1.011101]
AdvancedTechnologyResearchandDevelopmentCenter,MitsubishiElectricCorporation,Amagasaki,Hyogo661-8661,Japan1 NanoscienceDevelopmentandSupportTeam,RIKEN,Wako,Saitama351-0198,Japan2 DepartmentofElectronicsandAppliedPhysics,TokyoInstituteofTechnology,Yokohama
226-8502,Japan* E-mailaddress:Nanjo.Takuma@ap.MitsubishiElectric.co.jp
Appl. Phys. Express Vol.1, No.1 (2008) 011102
Continuous-Wave Operation of Blue Laser Diodes Based on Nonpolar m-Plane Gallium NitrideMasashiKubota,KuniyoshiOkamoto,TaketoshiTanaka,andHiroakiOhta*
(ReceivedNovember1,2007;acceptedNovember12,2007;publishedonlineDecember28,2007)
Thecontinuous-wave(cw)operationofm-planeInGaN-basedblue
(460nm)laserdiodes(LDs)hasbeenachieved.Thethresholdcurrentand
thecorrespondingthresholdcurrentdensitywere40mAand5.0kA/cm2,
respectively,witha459nmlasingwavelengthundercwoperation.The
electroluminescencepeakwavelengthshift inpulsedmodewasonly
10nm(58meV), fromspontaneousemission(at0.3mA)tostimulated
emission(at32mA),whichisextremelysmallwhencomparedwiththat
ofc-planeblueLDs.Thisisfirstclearexperimentaldemonstrationofthe
advantage in fabricatingnonpolar InGaN-basedLDsbeyondtheblue
region.[DOI:10.1143/APEX.1.011102]
ResearchandDevelopmentHeadquarters,ROHMCo.,Ltd.,Kyoto615-8585,Japan* E-mailaddress:Hiroaki.Ota@dsn.rohm.co.jp
Appl. Phys. Express Vol.1, No.1 (2008) 011103
Effects of Traps Formed by Threading Dislocations on Off-State Breakdown Characteristics in GaN Buffer Layer in AlGaN/GaN Heterostructure Field-Effect TransistorsAkihiroHinoki,JunjirohKikawa1,TomoyukiYamada1,TadayoshiTsuchiya1,ShinichiKamiya1,MasahitoKurouchi1,KenichiKosaka,TsutomuAraki,AkiraSuzuki1,2,andYasushiNanishi(ReceivedNovember6,2007;acceptedNovember16,2007;publishedonlineDecember28,2007)
Theoff-statebreakdowncharacteristicsofGaNlayerswithdifferent
thicknessesfrom0.2to2µmgrownbymetalorganicchemicalvapor
depositiononSiCsubstrateswerediscussedusingthespace-charge-
limitedcurrentconductionmechanism.Withdecreasingthicknessofthe
GaNlayer,theoff-statebreakdownvoltageincreased.Thetrapdensity
intheGaNlayerwasestimatedfromthetraps-filled-limitvoltage,which
determinedtheoff-statebreakdownvoltage.Wefoundthatthethus-
estimatedtrapdensity increasedwithdecreasingthicknessoftheGaN
layer.Ahigherdensityofthreadingdislocations inthethinnersamples
wasconfirmedbytransmissionelectronmicroscopyobservations.These
resultssuggestthatthetrapsformedbythethreadingdislocationsinflu-
encetheoff-statebreakdownvoltageoftheGaNlayer.
[DOI:10.1143/APEX.1.011103]
DepartmentofPhotonics,RitsumeikanUniversity,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,Japan1 R&DAssociationforFutureElectronDevices,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,
Japan2 ResearchOrganizationofScienceandEngineering,RitsumeikanUniversity,1-1-1Noji-
Higashi,Kusatsu,Shiga525-8577,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 011104
Blue Laser Diodes Fabricated on m-Plane GaN SubstratesYuhzohTsuda,MasatakaOhta,PabloO.Vaccaro,ShigetoshiIto,ShuichiHirukawa,YoshinobuKawaguchi,YoshieFujishiro,YoshiyukiTakahira,YoshihiroUeta,TeruyoshiTakakura,andTakayukiYuasa(ReceivedOctober30,2007;revisedDecember11,2007;acceptedDecember15,2007;publishedonlineJanuary11,2008)
Blue laserdiodes (LDs)werefabricatedonm-planeorientedGaN
substratesbyatmospheric-pressuremetalorganicchemicalvapordeposi-
tion.Typicalthresholdcurrentforstimulatedemissionatawavelengthλ
of463nmwas69mA.Blueshiftofthespontaneousemissionpeakwith
increasinginjectioncurrentwasexaminedinLDsfabricatedonm-and
c-planeGaNsubstrates.Blueshiftsforthem-planeLD(λ=463nm)and
thec-planeLD(λ=454nm)withaninjectioncurrentdensity justbelow
thresholdwereabout10and26nm,respectively.Theseresultsconfirm
that theblueshift inquantum-wells fabricatedonm-planeoriented
substrates is smaller thanonc-planeorientedsubstratesdue to the
absenceofpolarization-inducedelectricfields.
[DOI:10.1143/APEX.1.011104]
AdvancedTechnologyResearchLaboratories,SharpCorporation,2613-1Ichinomoto-cho,Tenri,Nara632-8567,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.1 (2008) 011105
Vertical GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistors on GaN Bulk SubstratesHirotakaOtake,KentaroChikamatsu,AtsushiYamaguchi,TatsuyaFujishima,andHiroakiOhta*
(ReceivedNovember5,2007;acceptedNovember12,2007;publishedonlineJanuary11,2008)
Completelyvertical trenchgatemetaloxidesemiconductor field-
effect transistors (MOSFETs)havebeenproducedusinggalliumnitride
(GaN)forthefirst time.TheseMOSFETsexhibitedenhancement-mode
operationwitha thresholdvoltageof3.7Vandanon-resistanceof
9.3mΩ·cm2.Thechannelmobilitywasestimatedtobe131cm2/(V·s)
whenall theresistancesexceptforthatofthechannelareconsidered.
Suchstructures,whichsatisfythekeywords“vertical”,“trenchgate”,
and“MOSFET”,willenableustofabricatepracticalGaN-basedpower
switchingdevices.[DOI:10.1143/APEX.1.011105]
ResearchandDevelopmentHeadquarters,ROHMCo.,Ltd.,Kyoto615-8585,Japan* E-mailaddress:Hiroaki.Ota@dsn.rohm.co.jp
Appl. Phys. Express Vol.1, No.1 (2008) 011106
Monolithic Polychromatic Light-Emitting Diodes Based on InGaN Microfacet Quantum Wells toward Tailor-Made Solid-State LightingMitsuruFunato*,TakeshiKondou,KeitaHayashi,ShotaroNishiura,MasayaUeda,YoichiKawakami,YukioNarukawa1,andTakashiMukai1(ReceivedNovember15,2007;acceptedDecember9,2007;publishedonlineJanuary17,2008)
Monolithicpolychromatic light-emittingdiodes (LEDs)basedon
micro-structured InGaN/GaNquantumwellsaredemonstrated.The
microstructureiscreatedthroughregrowthonSiO2maskstripesalong
the[11–00]directionandconsistsof(0001)and{112
–2}facets.TheLEDs
exhibitpolychromaticemission,includingwhite,duetotheadditivecolor
mixtureoffacet-dependentemissioncolors.Alteringthegrowthcondi-
tionsandmaskgeometryeasilycontrols theapparentemissioncolor.
Furthermore,simulationspredicthigh lightextractionefficienciesdue
totheir three-dimensionalstructures.Thoseobservationssuggest that
theproposedphosphor-freeLEDsmayleadtohighlyefficientsolid-state
lighting inwhichthecolorspectraof lightsourcesaresynthesizedto
satisfyspecificrequirementsforilluminations.
[DOI:10.1143/APEX.1.011106]
DepartmentofElectronicScienceandEngineering,KyotoUniversity,Kyoto615-8510,Japan1 NitrideSemiconductorResearchLaboratory,NichiaCorporation,Tokushima774-8601,
Japan* E-mailaddress:funato@kuee.kyoto-u.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 011201
Germanium Nitride Interfacial Layer for Chalcogenide Random Access Memory ApplicationsJieShen1,2,*,BoLiu1,**,ZhitangSong1,ChengXu1,2,FengRao1,2,ShuangLiang1,2,SonglinFeng1,andBomyChen3
(ReceivedNovember8,2007;acceptedNovember15,2007;publishedonlineDecember28,2007)
Thisworkreportsontheperformance improvementofachalco-
geniderandomaccessmemorydevicebyapplyinggermaniumnitrideas
aninterfacial layer.Thedevicewithan8-nm-thickGeNfilmwasfabri-
catedusingstandard0.18µmcomplementarymetaloxidesemiconductor
technology.Theas-depositedGeNis in theamorphousstateandhas
asmoothsurface.Anelectrical testshowedthatthisN-deficient layer
inducesalowerthresholdvoltageduringtheoperation.Itisbelievedthat
thereductionmainlyoriginatedfromtheexcellentinterfacialproperties,
highelectricalresistivity,andlowthermalconductivityofGeN,whichis
wouldbeaprospectiveinterfacialmaterialinCRAMdevices.
[DOI:10.1143/APEX.1.011201]
1 LaboratoryofNanotechnology,ShanghaiInstituteofMicrosystemandInformationTechnology,ChineseAcademyofSciences,Shanghai200050,P.R.China
2 GraduateUniversityofChineseAcademyofSciences,Beijing100039,P.R.China3 SiliconStorageTechnology,Inc.,1171SonoraCourt,Sunnyvale,CA94086,U.S.A.* E-mailaddress:shenjie@mail.sim.ac.cn**E-mailaddress:liubo@mail.sim.ac.cn
Appl. Phys. Express Vol.1, No.1 (2008) 011202
Vertical Solar-Blind Deep-Ultraviolet Schottky Photodetectors Based on β-Ga�O� SubstratesTakayoshiOshima*,TakeyaOkuno,NaokiArai1,NorihitoSuzuki1,ShigeoOhira1,andShizuoFujita2
(ReceivedNovember12,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Avertical-typeSchottkyphotodetectorbasedona (100)-oriented
β-Ga2O3substratehasbeenfabricatedwithsimpleprocessesofthermal
annealingandvacuumevaporation.Thephotodetectorexhibitedarecti-
fication ratiohigher than106at±3V,andshoweddeep-ultraviolet-
lightdetectionatreversebias.Thespectralresponseshowedsolar-blind
sensitivitywithhighphotoresponsivitiesof2.6–8.7A/Watwavelengths
of200–260nm.Thesevalueswere35–150timeshigher thanthose
derivedassumingtheinternalquantumefficiencytobeunity.Thisfact
isattributedtothecarriermultiplicationoccurringinthehighlyresistive
surfaceregionthat issubject toahigh internalelectric fieldofabout
1.0MV/cmatthereversebiasof10V.[DOI:10.1143/APEX.1.011202]
DepartmentofElectronicScienceandEngineering,KyotoUniversity,Katsura,Nishikyo-ku,Kyoto615-8510,Japan1 NipponLightMetalCompany,Ltd.,Kambara,Shimizu-ku,Shizuoka421-3291,Japan2 GraduateSchoolofEngineering,KyotoUniversity,Katsura,Nishikyo-ku,Kyoto615-8520,
Japan* E-mailaddress:t-oshima@iic.kyoto-u.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.1 (2008) 011301
Current-Driven Domain Wall Motion in CoCrPt Wires with Perpendicular Magnetic AnisotropyHironobuTanigawa,KoutaKondou,TomohiroKoyama,KunihiroNakano,ShinyaKasai,NorikazuOhshima1,ShunsukeFukami1,NobuyukiIshiwata1,andTeruoOno(ReceivedNovember5,2007;acceptedNovember12,2007;publishedonlineJanuary11,2008)
We report thedirectobservationofcurrent-drivendomainwall
(DW)motioninaCoCrPtwirewithperpendicularmagneticanisotropy.
MagneticforcemicroscopyshowedthatasingleDWintroducedinthe
wireisdisplacedbackandforthbypositiveandnegativepulsedcurrent.
This is the firstdemonstrationof thecurrent-drivenDWmotion ina
metallicmagneticwirewithperpendicularmagneticanisotropy in the
absenceofamagneticfield.[DOI:10.1143/APEX.1.011301]
InstituteforChemicalResearch,KyotoUniversity,Uji,Kyoto611-0011,Japan1 DevicePlatformsResearchLaboratories,NECCorporation,1120Shimokuzawa,Sagamihara,
Kanagawa229-1198,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 011401
On Effects of Gate Bias on Hole Effective Mass and Mobility in Strained-Ge Channel StructuresKentarouSawano,YugoKunishi,YuuSatoh,KiyohikoToyama1,KeisukeArimoto2,ToruOkamoto1,NoritakaUsami3,KiyokazuNakagawa2,andYasuhiroShiraki(ReceivedNovember6,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Theeffectsofgatebiasonholeeffectivemass(m*)andHallmobility
werestudiedinstrained-Gechannelmodulation-dopedstructures.Shub-
nikov–deHaasoscillationswereanalyzedwithandwithoutthebiasand
asignificantm* increasefrom0.15to0.22m0wasobservedwiththe
increase inthecarrierdensityduetothestrongnonparabolicityofthe
valenceband.This isacleardemonstrationthatmodificationofcarrier
densityviagatingconsiderablyaffectsm*,whichmayhavecriticaleffects
ondeviceproperties.ThegatebiasdependenceofHallmobilitywasalso
investigatedandthedominantscatteringmechanismwasclarified in
varioustemperatureandcarrierdensityregions.
[DOI:10.1143/APEX.1.011401]
ResearchCenterforSiliconNano-Science,AdvancedResearchLaboratories,MusashiInstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan1 DepartmentofPhysics,UniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-0033,
Japan2 CenterforCrystalScienceandTechnology,UniversityofYamanashi,7Miyamae-cho,Kofu
400-0021,Japan3 InstituteforMaterialResearch,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai
980-8577,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 011501
Piezoelectric Properties of (K,Na)NbO� Films Deposited by RF Magnetron SputteringKenjiShibata,FumihitoOka,AkioOhishi,TomoyoshiMishima,andIsakuKanno1(ReceivedNovember7,2007;acceptedDecember3,2007;publishedonlineJanuary11,2008)
High-piezoelectricity lead-free filmsof (K,Na)NbO3 (KNN)were
successfullydepositedonPt /MgOandPt / Ti / SiO2 /SisubstratesbyRF
magnetronsputtering.TheKNNfilmwasepitaxiallygrownonPt /MgO
withahigh<001>orientation in thepseudo-cubicperovskitestruc-
ture.TheKNNfilmonPt / Ti / SiO2 /Siwaspolycrystallinewithaprefer-
ential<001>orientation inthepseudo-cubicperovskitestructure.The
piezoelectricpropertiesoftheKNNfilmsweredeterminedfromthetip
displacementofKNN/Pt /MgOorKNN/Pt / Ti / SiO2 /Siunimorphcantile-
vers.Thetransversepiezoelectriccoefficientse31*(d31 /s11
E)oftheKNN
filmsonPt /MgOandPt / Ti / SiO2 /Siwerecalculatedtobe-3.6and-5.5C/
m2,respectively,whichareamongst thehighestvalues forKNNfilms
everreported.[DOI:10.1143/APEX.1.011501]
AdvancedElectronicMaterialsResearchDepartment,ResearchandDevelopmentLaboratory,HitachiCable,Ltd.,3550Kidamari,Tsuchiura,Ibaraki300-0026,Japan1 DepartmentofMicroEngineering,KyotoUniversity,Yoshida-honmachi,Sakyo-ku,Kyoto
606-8501,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 011502
Valence State of Mn-Doped BiFeO� –BaTiO� Ceramics Probed by Soft X-ray Absorption SpectroscopyTohruHiguchi1,2,WataruSakamoto3,NaoyukiItoh3,TetsuoShimura3,TakeshiHattori2,andToshinobuYogo3
(ReceivedNovember16,2007;acceptedDecember3,2007;publishedonlineJanuary11,2008)
The valence state ofMn-dopedBiFeO3 –BaTiO3 ceramics has
beenprobedbysoftX-rayabsorptionspectroscopy (XAS).Mn-doped
BiFeO3 –BaTiO3hasvalencestatesofFe3+andTi4+,althoughBiFeO3
andMn-dopedBiFeO3havemixedvalence statesofFe2+andFe3+.
TheMn2p-XASpeakofMn-dopedBiFeO3 –BaTiO3 locatesata lower
energysidethanthatofMn-dopedBiFeO3thatcorrespondstotheMn3+
valencestate.ThesefindingsmayindicatethattheFe3+valencestateof
Mn-dopedBiFeO3 –BaTiO3isstabilizedbychargetransferfromtheMn
3dstatetotheFe3dstatethroughtheTi3dstateinBaTiO3.
[DOI:10.1143/APEX.1.011502]
1 AdvancedLightSource,LawrenceBerkeleyNationalLaboratory,1CyclotronRoad,MS7R0222,Berkeley,CA94720,U.S.A.
2 DepartmentofAppliedPhysics,TokyoUniversityofScience,1-3Kagurazaka,Shinjuku,Tokyo162-8601,Japan
3 EcoTopiaScienceInstitute,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.1 (2008) 011701
Superconductor-based Light Emitting Diode: Demonstration of Role of Cooper Pairs in Radiative Recombination ProcessesYujiroHayashi1,*,KazunoriTanaka2,3,TatsushiAkazaki3,4,MasafumiJo1,HidekazuKumano1,3,andIkuoSuemune1,3
(ReceivedNovember8,2007;acceptedDecember9,2007;publishedonlineJanuary17,2008)
A lightemittingdiodewith superconductingNbelectrodeswas
fabricatedto investigate thecontributionofcooperpairs toradiative
recombination inasemiconductor.Electroluminescenceobservedfrom
theactive layer inwhichelectroncooperpairsandnormalholesare
injectedwasdrasticallyenhancedat the temperature lower thanthe
superconductingtransitiontemperatureoftheNbelectrodes.Thisisthe
firstexperimentalevidencethatcooperpairsenhanceradiativerecombi-
nationsbythesuperradianceeffect.[DOI:10.1143/APEX.1.011701]
1 ResearchInstituteforElectronicScience,HokkaidoUniversity,Sapporo001-0021,Japan2 CentralLaboratory,HamamatsuPhotonics,Hiraguchi,Hamamatsu434-8601,Japan3 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan4 NTTBasicResearchLaboratory,Morinosato-Wakamiya,Atsugi,Kanagawa243-0198,Japan* E-mailaddress:yhayashi@es.hokudai.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 011801
Dual Self-Aligned Vertical Multichannel Organic TransistorsHidenoriNaruse,ShigekiNaka,andHiroyukiOkada*
(ReceivedNovember1,2007;acceptedNovember16,2007;publishedonlineDecember28,2007)
Adual self-alignedverticalmultichannelorganic transistor (DSA-
VMCOT)isproposedanddemonstrated.Thelayoutsoftheshadowgate
and transparent source/drainaresequentiallydeterminedusingdual
back-surfaceexposure.Vertical100-nmchannelandmultichannelstruc-
turesareobtainedusinginterdigitalgateelectrodes.Thisdeviceconcept
ispromisingforuseasabackplanewithhighcurrentdrivingcapability.
[DOI:10.1143/APEX.1.011801]
GraduateSchoolofScienceandEngineering,UniversityofToyama,3190Gofuku,Toyama930-8555,Japan* E-mailaddress:okada@eng.u-toyama.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 012001
Planar Avalanche Photodiode for Long-Haul Single-Photon Optic Fiber CommunicationsEijiYagyu*,KoheiSugihara,TsuyoshiNishioka1,MitsuruMatsui1,KiichiYoshiara,andYasunoriTokuda(ReceivedNovember2,2007;acceptedNovember20,2007;publishedonlineDecember28,2007)
Wepresentahigh-performanceplanarGaInAs/InPavalanchephoto-
diode(APD)forlong-haulsingle-photonopticfibercommunications,that
is,quantumcryptography.TheAPDsforsingle-photoncommunications
requireahighsingle-photondetectionefficiency(ηdet)relatingtobitrate
andalowratioofdarkcountprobability(Pdc)toηdetlimitingcommuni-
cationdistance.WefabricatedtheAPDwiththecombinationofalong
multiplicationregionlengthandalowcarriersheetdensityonthebasis
ofnumericalanalysis.ThePdc /ηdetmonotonicallydecreasedwithopera-
tiontemperaturelowered,andtheratioreached5.9×10-6withtheηdet
of13%at77K.ThePdcwas7.7×10-7,whichcorrespondstoadark
countrateof0.38kHz.TheusefulAPDandtheeffectivelayerdesignare
reported.[DOI:10.1143/APEX.1.012001]
AdvancedTechnologyR&DCenter,MitsubishiElectricCorporation,Amagasaki,Hyogo661-8661,Japan1 InformationTechnologyR&DCenter,MitsubishiElectricCorporation,Kamakura,Kanagawa
247-8501,Japan* E-mailaddress:Yagyu.Eiji@cb.MitsubishiElectric.co.jp
Appl. Phys. Express Vol.1, No.1 (2008) 012002
Two-Dimensional Photonic Crystal Composed of Ordered Polymer Nanopillar Arrays with High Aspect Ratios Using Anodic Porous Alumina TemplatesTakashiYanagishita1,*,KazuyukiNishio1,2,andHidekiMasuda1,2
(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Two-dimensional (2D)photonic crystals composedofordered
polymernanopillararrayswerefabricatedusinganodicporousalumina
templates.Forthepreparationof2Dphotoniccrystalswithhighaspect
ratios,polymerpillararrays, inwhichbothendsofnanopillarswere
supportedbysupportinglayers,wereintroduced.Thediameter,interval
and lengthofnanopillararrayscouldbecontrolledbychanging the
preparationconditionsofanodicporousaluminatemplates.Thereflec-
tionpropertiesoftheorderedpolymernanopillararrayobtainedexhib-
itedastopbandinthespectrum,whichcorrespondstothebandgapin
the2Dphotoniccrystals.[DOI:10.1143/APEX.1.012002]
1 KanagawaAcademyofScienceandTechnology,5-4-30Nishihashimoto,Sagamihara,Kanagawa229-1131,Japan
2 DepartmentofAppliedChemistry,TokyoMetropolitanUniversity,1-1Minamiosawa,Hachioji,Tokyo192-0397,Japan
* E-mailaddress:tyanagishita@r7.dion.ne.jp
Appl. Phys. Express Vol.1, No.1 (2008) 012003
Tunable Liquid Crystal Laser Using Distributed Feedback Cavity Fabricated by Nanoimprint LithographyRyotaroOzaki,ToshikazuShinpo,KatsumiYoshino1,MasanoriOzaki2,andHiroshiMoritake(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Electricaltuningoflaserwavelengthisdemonstratedusingaliquid-
crystal /polymergrating fabricatedbynanoimprint lithography.Laser
emissionoccursatawavelengthnear700nm,whichcorrespondstothe
firstorderofa200nmperiodgrating.Withincreasingappliedvoltage,
thelasingspectrumbeginstoshifttoshorterwavelengthsat10V,and
thena10nmshiftisachievedwithanappliedvoltageof30V.Thisisdue
totherefractive indexchangeoftheliquidcrystal inthetrenchofthe
polymergratingbyfield-inducedmolecularreorientation.
[DOI:10.1143/APEX.1.012003]
DepartmentofElectricalandElectronicEngineering,NationalDefenseAcademy,1-10-20Hashirimizu,Yokosuka,Kanagawa239-8686,Japan1 ShimaneInstituteforIndustrialTechnology,1Hokuryo-cho,Matsue690-0816,Japan2 DivisionofElectrical,ElectronicandInformationEngineering,GraduateSchoolof
Engineering,OsakaUniversity,2-1Yamada-Oka,Suita,Osaka565-0871,Japan
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.1 (2008) 012004
Generation of Intense and Monochromatic Terahertz Radiation from Coherent Longitudinal Optical Phonons in GaAs/AlAs Multiple Quantum Wells at Room TemperatureMasaakiNakayama,Shuh-ichiIto,KohjiMizoguchi1,ShingoSaito2,andKiyomiSakai2(ReceivedNovember1,2007;acceptedDecember7,2007;publishedonlineJanuary11,2008)
Wehaveinvestigatedtime-domainsignalsofterahertz(THz)radia-
tion fromcoherent longitudinal-optical (LO)phonons inGaAs/AlAs
multiplequantumwellsatroomtemperature,utilizinganopticalgating
methodwithaphotoconductivedipoleantenna.Ithasbeenfoundthat
an intenseandmonochromaticTHzwavewithafrequencyof8.7THz
isgenerated fromcoherentGaAs-likeLOphononsunder thecondi-
tionthattheenergyspacingbetweenthefundamentalheavy-holeand
light-holeexcitonsistunedtotheLO-phononenergy.Thepump-energy
andpump-powerdependencesof theTHz-radiation intensity indicate
thattheimpulsiveinterferenceoftheheavy-holeandlight-holeexcitons
dominatesthegenerationprocess.[DOI:10.1143/APEX.1.012004]
DepartmentofAppliedPhysics,GraduateSchoolofEngineering,OsakaCityUniversity,Sugimoto,Sumiyoshi-ku,Osaka558-8585,Japan1 DepartmentofPhysicalScience,GraduateSchoolofScience,OsakaPrefectureUniversity,
Gakuen-cho,Naka-ku,Sakai599-8531,Japan2 NationalInstituteofInformationandCommunicationsTechnology,Koganei,Tokyo
184-8795,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 012005
Development of Electrooptic Modulator for Advanced Ground-Based Gravitational Wave Telescopes Using Stoichiometric MgO-Doped LiNbO� CrystalsNoriakiOhmae*,KoheiTakeno1,ShigenoriMoriwaki,andNorikatsuMio(ReceivedNovember2,2007;acceptedNovember20,2007;publishedonlineJanuary11,2008)
Wehavedevelopedanelectroopticmodulator (EOM)usingstoi-
chiometricMgO-dopedLiNbO3 (MgO-dopedSLN)crystals,andevalu-
atedthisEOMforthephasecontrolofahigh-powerlaserwhosepower
isover100W.Wesucceededinthephasemodulationofa100Wlaser
withoutadecreaseinphasemodulationindex,duetoanonlinearoptical
effect,whichcanoccurwhenahigh-powerlaserbeamenterstheEOM.
Wealsoestimatedwavefrontdistortionscausedbypassingthroughthe
EOMwithaShack –Hartmannwavefrontsensor,andfoundthat the
additionalwavefrontdistortionwasnegligible.Thus,weconfirmedthat
MgO-dopedSLNcrystalsareasuitablematerialforuseinahigh-power
lasersystem.[DOI:10.1143/APEX.1.012005]
DepartmentofAdvancedMaterialsScience,UniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8561,Japan1 NationalInstituteofAdvancedIndustrialScienceandTechnology,1-2-1Namiki,Tsukuba,
Ibaraki305-8564,Japan* E-mailaddress:kk66109@mail.ecc.u-tokyo.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 012006
Visible Anisotropic Deformation of Chalcogenide Glass by Illumination of Linearly Polarized LightKeijiTanaka(ReceivedNovember2,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
It has been discovered that illumination of linearly-polarized
bandgaplightproducesvisible-scaleanisotropicdeformationsinacova-
lentchalcogenideglassAs2S3.X-raydiffractionandRaman-scattering
measurementsfordeformingAs2S3flakesdetectnomicroscopicstruc-
turalchanges.Measurementsofopticaltorqueindeformingflakesand
comparativeexposureexperimentsforcrystallineAs2S3andamorphous
Sesuggest that theanisotropicdeformationoccurs throughradiation
force,photoinducedbirefringence,andphotoinducedfluidity.
[DOI:10.1143/APEX.1.012006]
DepartmentofAppliedPhysics,GraduateSchoolofEngineering,HokkaidoUniversity,Kita-ku,Sapporo060-8628,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 012007
Kerr-Lens Mode-Locked Diode-Pumped Yb:YAG Laser with the Transverse Mode Passively StabilizedSadaoUemura*andKenjiTorizuka(ReceivedNovember5,2007;acceptedNovember27,2007;publishedonlineJanuary11,2008)
WehavedevelopedaKerr-lensmode-lockeddiode-pumpedYb:YAG
laser inwhichthe transversemode ispassivelystabilized.Themode-
lockingschemecanbeusedforvariousdiode-pumpedYb-dopedbulk
lasers.Thepulsedurationisasshortas100fs,which is toourknowl-
edgetheshortestpulseeverproducedfromanYb:YAGlaser.Thecenter
wavelengthandlaseroutputpowerare1051nmand151mW,respec-
tively.[DOI:10.1143/APEX.1.012007]
PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Central2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:s.uemura@aist.go.jp
Appl. Phys. Express Vol.1, No.1 (2008) 012008
Realization of All-fiber Tunable Filter and High Optical Power Blocker Using Thinned Fiber Bragg Gratings Coated with Carbon NanotubesKienT.Dinh*,Yong-WonSong1,ShinjiYamashita1,andSzeY.Set2
(ReceivedNovember13,2007;acceptedDecember7,2007;publishedonlineJanuary11,2008)
Weproposeandcreateanovelstructureformedwiththinnedfiber
Bragggratingsandcarbonnanotubesutilizingtheiropticalabsorption
characteristics.WeshowthatthereflectionbandofthefiberBragggrat-
ingscanbeshiftedbycontrollingthein-lineopticalpower.Weusethe
structuretorealizetwoapplicationsnamelyanall-fibertunablefilterand
ahigh-optical-powerblocker.[DOI:10.1143/APEX.1.012008]
GraduateSchoolofFrontierSciences,UniversityofTokyo,Tokyo113-8656,Japan1 DepartmentofElectronicsEngineering,UniversityofTokyo,Tokyo113-8656,Japan2 AlnairLaboratoriesCorporation,Tokyo154-0005,Japan* E-mailaddress:kien@sagnac.t.u-tokyo.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.1 (2008) 012009
Propagation of Terahertz Pulses on Coplanar Strip-lines on Low Permittivity Substrates and a Spectroscopy ApplicationShinjiYanagi,MasayukiOnuma,JiroKitagawa,andYutakaKadoya*
(ReceivedNovember22,2007;acceptedDecember9,2007;publishedonlineJanuary17,2008)
Theauthorshave investigated thepropagationcharacteristicsof
theterahertzelectricalpulsesonthecoplanarstrip-lines(CPSs)madeon
lowpermittivitysubstrates.Bytheuseofacommerciallyavailableplastic
whosepermittivity isabout2.3 in1–3THz, the radiation losscould
bemade low,andthe totalattenuationofabout0.2neper/mmwas
achievedat1THz.Asaresult,thespectrareaching3THzwithadynamic
rangeofabout60dBwererealizedevenafter the1mmpropagation.
UsingtheCPSdevice,aspectroscopyofbiotinpowderisdemonstrated
overafrequencyrangeupto2THz.[DOI:10.1143/APEX.1.012009]
GraduateSchoolofAdvancedSciencesofMatter,HiroshimaUniversity,1-3-1Kagamiyama,Higashihiroshima,Hiroshima739-8530,Japan* E-mailaddress:kd@hiroshima-u.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 013001
Tunneling Current–Voltage Characteristics of Graphene Field-Effect TransistorVictorRyzhii1,3,MaximRyzhii1,3,andTaiichiOtsuji2,3
(ReceivedNovember2,2007;acceptedNovember25,2007;publishedonlineDecember28,2007)
Wedevelopananalyticaldevicemodelforagraphenefield-effect
transistor.Usingthismodel,wecalculateitscurrent–voltagecharacteris-
ticsatsufficientlyhighgatevoltageswhenan–p–n(p–n–p)lateraljunc-
tionisformedinthetransistorchannelandthesource–draincurrentis
associatedwiththeinterbandtunnelingthroughthisjunction.
[DOI:10.1143/APEX.1.013001]
1 ComputerSolidStatePhysicsLaboratory,UniversityofAizu,Aizu-Wakamatsu,Fukushima965-8580,Japan
2 ResearchInstituteforElectricalCommunication,TohokuUniversity,Sendai980-8577,Japan3 CREST,JapanScienceandTechnologyAgency,Tokyo107-0075,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 014001
Growth of Single-Walled Carbon Nanotubes from Ceramic Particles by Alcohol Chemical Vapor DepositionHuapingLiu1,*,DaisukeTakagi1,HiroshiOhno1,ShoheiChiashi1,TomohitoChokan1,andYoshikazuHomma1,2,**
(ReceivedOctober27,2007;acceptedDecember10,2007;publishedonlineJanuary11,2008)
Al2O3ceramicnano-particles,whichwere regardedasan inac-
tivecatalyst inthegrowthofcarbonnanotubesinthepast,havebeen
preparedas thecatalyst forsingle-walledcarbonnanotube (SWCNT)
growthusinganalcohol chemical vapordepositionmethod.Dense
SWCNTshavebeensuccessfullysynthesized,indicatingthatAl2O3serves
asanefficientcatalyst.Moreover,itwasfoundthatmanySWCNTswere
alsogrownfrom irregular largeAl2O3particles ranging fromseveral
tensofnanometerstohundredsofnanometers,whichhasneverbeen
observedinthecaseofmetalliccatalystparticles.Theseresultsgivemore
insightsintotheroleofcatalystinSWCNTgrowth.
[DOI:10.1143/APEX.1.014001]
1 DepartmentofPhysics,TokyoUniversityofScience,Shinjuku,Tokyo162-8601,Japan2 CREST,JapanScienceandTechnologyAgency,Chiyoda,Tokyo102-0075,Japan* E-mailaddress:hliu@rs.kagu.tus.ac.jp**E-mailaddress:Homma@rs.kagu.tus.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 014002
Behavior of Catalyst Particle at Tip of Carbon Nanotube during Field EmissionTadashiFujieda*,MakotoOkai,KishioHidaka,HiroakiMatsumoto1,andHiroshiTokumoto2
(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Acatalystparticleat the tipofamulti-walledcarbonnanotube
(MWNT)duringfieldemissioninsideatransmissionelectronmicroscope
wasobserved in-situ.Theparticlestreamedfromthetip likea liquid
astheemissioncurrentabruptly increasedfrom20to40µA.Thiswas
duetothetemperatureriseatthetipoftheMWNT,resultingfromthe
increasedemissioncurrentanddipolemomentintheparticlecausedby
theelectric field.Maintenanceof thishighemissioncurrent ledtoan
electricaldischarge,whichseverelydamagedtheMWNTelectronemitter.
Underhighemissioncurrents, inparticular,thecatalystparticlecaused
anunstableemission.[DOI:10.1143/APEX.1.014002]
MaterialsResearchLaboratory,Hitachi,Ltd.,Hitachi,Ibaraki319-1292,Japan1 HitachiHigh-TechManufacturingandServiceCorporation,Hitachinaka,Ibaraki312-0033,
Japan2 NanotechnologyResearchCenter,ResearchInstituteforElectronicScience,Hokkaido
University,Sapporo001-0021,Japan* E-mailaddress:tadashi.fujieda.yv@hitachi.com
Appl. Phys. Express Vol.1, No.1 (2008) 014003
Vapor–Liquid–Solid Growth of Small- and Uniform-Diameter Silicon Nanowires at Low Temperature from Si�H�SaeedAkhtar1,KoichiUsami1,YoshishigeTsuchiya1,2,HiroshiMizuta2,3,andShunriOda1,2,*
(ReceivedNovember12,2007;acceptedDecember7,2007;publishedonlineJanuary11,2008)
Wereport350°Casacriticalgrowthtemperatureforovercoming
theaggregationofgold (Au) in thesynthesisofhigh-density silicon
nanowires (SiNWs)withcontrolleddiameters inavapor – liquid–solid
(VLS)mechanismby the low-temperaturedecompositionofSi2H6.
Low-temperaturegrowthisconsideredessentialforpreservingtheinitial
distributionofAudroplets(8±5nm)duringSiNWnucleationwithsmall
(12nm)anduniform(±5nm)diameters.Au–Sieutecticsincreaseinsize
withaggregationathightemperatures,resultinginSiNWswithlargeand
randomdiameters.Thecrystalquality,defectformation,andmorphology
ofthewires,growninthe(111)direction,aresizedependent.
[DOI:10.1143/APEX.1.014003]
1 QuantumNanoelectronicsResearchCenter,TokyoInstituteofTechnology,2-12-1O-okayama,Meguro-ku,Tokyo152-8552,Japan
2 SolutionOrientedResearchforScienceandTechnology,JST,Kawaguchi,Saitama332-0012,Japan
3 SchoolofElectronicsandComputerScience,SouthamptonUniversity,Highfield,SouthamptonSO171BJ,U.K.
* E-mailaddress:soda@pe.titech.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.1 (2008) 015001
Development of �H–SiC Epitaxial Growth Technique Achieving High Growth Rate and Large-Area UniformityMasahikoIto*,LiutaurasStorasta,andHidekazuTsuchida(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)
Averticalhot-wallepi-reactorthatmakes itpossibletosimultane-
ouslyachieveahighgrowthrateand large-areauniformityhasbeen
developed.Amaximumgrowthrateof250µm/h isachievedwitha
mirror-likemorphologyat1650°C.Underamodifiedepi-reactorsetup,
athicknessuniformityof1.1%andadopinguniformityof6.7%fora
65-mm-radiusareaareachievedwhilemaintainingahighgrowthrate
of79µm/h.Alowdopingconcentrationof~1×1013cm-3isobtainedfor
a50-mm-radiusarea.The low-temperaturephotoluminescence (LTPL)
spectrumshowsthepredominanceoffreeexcitonpeakswithonlyfew
impurity-relatedpeaksandtheL1peakbelowdetectionlimit.Thedeep
leveltransientspectroscopy(DLTS)measurementforanepilayergrown
at80µm/hshowslowtrapconcentrationsofZ1/2:1.2×1012andEH6/7:
6.3×1011cm-3.A280-µm-thickepilayerwithaRMSroughnessof0.2nm
andacarrierlifetimeof~1µsisobtained.
[DOI:10.1143/APEX.1.015001]
CentralResearchInstituteofElectricPowerIndustry,2-6-1Nagasaka,Yokosuka,Kanagawa240-0196,Japan* E-mailaddress:m-ito@criepi.denken.or.jp
Appl. Phys. Express Vol.1, No.1 (2008) 015002
High Mobility Titanium-Doped In�O� Thin Films Prepared by Sputtering/Post-Annealing TechniqueRyotaHashimoto,YoshiyukiAbe1,andTokioNakada(ReceivedNovember1,2007;acceptedDecember15,2007;publishedonlineJanuary17,2008)
High-electron-mobilityTi-dopedIn2O3(ITiO)thinfilmswereprepared
onsoda-limeglasssubstratesbyrfmagnetronsputteringfollowedbya
post-annealingprocess.Bothcarrierconcentrationandelectronmobility
wereconsiderablyimprovedbyannealinginavacuumat530°C.Ahighest
electronmobilityof105cm2V-1s-1witharesistivityof1.95×10-4 Ωcm
wasobtainedforanannealedITiOthinfilm.TheITiOthinfilmexhibited
anoptical transmissionofapproximately80%atwavelengthsranging
from400to1800nm.Post-annealinginavacuumisoneoftheeffective
methodsforimprovingtheelectricalpropertiesofITiOthinfilmswithout
sacrificingopticaltransmission.[DOI:10.1143/APEX.1.015002]
DepartmentofElectricalEngineeringandElectronics,AoyamaGakuinUniversity,5-10-1Fuchinobe,Sagamihara,Kanagawa229-8558,Japan1 IchikawaResearchLaboratory,SumitomoMetalMiningCo.,Ltd.,Nakakokubun,Ichikawa,
Chiba272-8588,Japan
Appl. Phys. Express Vol.1, No.1 (2008) 014004
Highly Sensitive Detection of Carbon Monoxide at Room Temperature Using Platinum-Decorated Single-Walled Carbon NanotubesWinaddaWongwiriyapan,SatoshiInoue,TatsuyaIto1,RyotaroShimazaki1,ToruMaekawa1,KengoSuzuki1,HiroshiIshikawa1,Shin-ichiHonda,KenjiroOura2,andMitsuhiroKatayama*
(ReceivedNovember13,2007;acceptedDecember3,2007;publishedonlineJanuary11,2008)
Wedemonstratedhighlysensitivedetectionofcarbonmonoxide(CO)
downto1ppmatroomtemperatureusingplatinum-decoratedsingle-
walledcarbonnanotubes(Pt-SWNTs).TheobtainedsensitivitytoCOwas
3–4ordershigherthanthevaluesreportedforfunctionalizedSWNTs,
andwasachievedbythecontrolleddepositionofPtnanoparticleson
SWNTs.For1–10ppmofCO, thesensor response linearly increased
withCOconcentration,affordingthequantitativedetectionofCOina
low-concentrationrange.Furthermore,Pt-SWNTsexhibiteddetection
selectivitytoCOagainstH2.Thesensingmechanismwasattributedto
electrondonationtotheSWNTsasaresultofCOoxidationonthePt
catalystsurface.[DOI:10.1143/APEX.1.014004]
DivisionofElectrical,ElectronicandInformationEngineering,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan1 NewCosmosElectricCo.,Ltd.,3-6-25Mitsuya-naka,Yodokawa-ku,Osaka532-0036,
Japan2 ResearchCenterforUltrahighVoltageElectronMicroscopy,OsakaUniversity,7-1
Mihogaoka,Ibaraki,Osaka567-0047,Japan* E-mailaddress:katayama@nmc.eei.eng.osaka-u.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 014005
Local Synthesis of Tungsten Oxide Nanowires by Current Heating of Designed Micropatterned WiresKeisukeNagato1,2,*,YusukeKojima1,KeigoKasuya3,HirokiMoritani1,TetsuyaHamaguchi1,andMasayukiNakao1
(ReceivedDecember4,2007;acceptedDecember15,2007;publishedonlineJanuary17,2008)
We locally synthesized tungstenoxidenanowires atpredeter-
minedpositionsbycurrentheatingofdesignedmicropatternedwires.
Thecurrentwireswere fabricated from tungsten thin filmandhad
twodifferentwidthsinthesamewire,andthenarrowersectionswere
heatedmorethanthewidersectionsduetothedifference inelectric
resistance.The temperatureof thenarrowersectionswascontrolled
tobeoptimalfornanowiresynthesisinanO2atmosphereinavacuum
chamber.Wedemonstrated thesynthesisofnanowiresoveranarea
ofapproximately1×1µm2andsuccessfullysynthesizednanowiresona
regular20by20arraywithnarrowsectionswith10µmpitch.
[DOI:10.1143/APEX.1.014005]
1 DepartmentofEngineeringSynthesis,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan
2 ResearchFellowoftheJapanSocietyforthePromotionofScience,8Ichibancho,Chiyoda-ku,Tokyo102-8472,Japan
3 CentralResearchLaboratory,Hitachi,Ltd.,1-280Higashi-koigakubo,Kokubunji,Tokyo185-8601,Japan
* E-mailaddress:nagato@hnl.t.u-tokyo.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.1 (2008) 015003
Photoluminescence from Epitaxial Films of Perovskite-type Alkaline-earth StannatesKazushigeUeda*,TsuyoshiMaeda,KensukeNakayashiki,KatsuhikoGoto,YutakaNakachi,HiroshiTakashima1,KenjiNomura2,KoichiKajihara2,**,andHideoHosono2
(ReceivedNovember20,2007;acceptedDecember18,2007;publishedonlineJanuary17,2008)
Theepitaxial filmsof the recentlydevelopedcalciumandstron-
tiumstannatesphosphorswithperovskiteor itsrelatedstructurewere
fabricatedby thepulsed-laseddepositionmethod.Thefilmswereall
highly transparent in thevisibleregion,andshowed intense lumines-
cenceofseveralcolorsunderultravioletexcitation.Lightscatteringat
thesubstrates'surfacesvariedtheappearanceofphotoluminescence.In
combinationwithepitaxial-film-growthtechnologiesformanyperovskite
functionalmaterials, theobtainedresultsprovideapromiseforfuture
developmentsofmultifunctionaloptoelectronicdevices.
[DOI:10.1143/APEX.1.015003]
KyushuInstituteofTechnology,1-1Sensui,Tobata,Kitakyushu804-8550,Japan1 NationalInstituteofAdvancedIndustrialScienceandTechnology,1-1-1Umezono,Tsukuba,
Ibaraki305-8568,Japan2 ERATO-SORST,JapanScienceandTechnologyAgency(JST),inFrontierCollaborative
ResearchCenter(FCRC),TokyoInstituteofTechnology,4259Nagatsuta,Midori,Yokohama226-8503,Japan
* E-mailaddress:kueda@che.kyutech.ac.jp**Presentaddress:DepartmentofAppliedChemistry,GraduateSchoolofUrban
EnvironmentalSciences,TokyoMetropolitanUniversity,1-1Minami-Osawa,Hachioji,Tokyo192-0397,Japan.
Appl. Phys. Express Vol.1, No.1 (2008) 015004
Exciton-derived Electron Emission from (00�) Diamond p–n Junction Diodes with Negative Electron AffinityDaisukeTakeuchi1,*,ToshiharuMakino1,Sung-GiRi1,NorioTokuda1,HiromitsuKato1,MasahikoOgura1,HideyoOkushi1,2,andSatoshiYamasaki1,3
(ReceivedNovember27,2007;acceptedDecember18,2007;publishedonlineJanuary17,2008)
Electronemissioncurrentwasobserved fromahydrogen-termi-
natedn-layerdiamondsurfaceofforwardbiaseddiamondp–njunction
diodes,whiletherewasnoelectronemissionfromthesamesurfaceafter
oxidization,suggestingthatthephenomenonisrelatedtonegativeelec-
tronaffinity (NEA)ofthehydrogen-terminateddiamondsurface.Since
electronsinthen-layerflowtowardtothep-layerduetoforwardbias,
theycannotdirectlycontributetotheemissioncurrentfromthen-layer
surface. Inviewofourpreviousresult thattheexciton-derivedphoto-
electronemissionwasobservedfromtheNEAdiamondsurfacebytotal
photoelectronyieldspectroscopy,thephenomenoncanbeexplainedas
electronemissionduetoexcitondiffusionattheforwardbias.
[DOI:10.1143/APEX.1.015004]
1 NanotechnologyResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan
2 SensorMaterialsCenter,NationalInstituteforMaterialsScience(NIMS),1-1Namiki,Tsukuba,Ibaraki305-0044,Japan
3 GraduateSchoolofPureandAppliedScience,UniversityofTsukuba,Tsukuba,Ibaraki305-8577,Japan
* E-mailaddress:d.takeuchi@aist.go.jp
Appl. Phys. Express Vol.1, No.1 (2008) 015005
Molecular Layer-by-Layer Growth of C�0 Thin Films by Continuous-Wave Infrared Laser DepositionSeiichiroYaginuma1,2,KenjiItaka2,3,MasamitsuHaemori4,MasaoKatayama1,3,KeijiUeno5,TsuyoshiOhnishi6,MikkLippmaa6,YujiMatsumoto1,3,andHideomiKoinuma2,3,4,*
(ReceivedNovember30,2007;acceptedDecember18,2007;publishedonlineJanuary17,2008)
Theobservationofreflectionhighenergyelectrondiffraction(RHEED)
oscillationshasbeenproved tobeakey toopenthenano-worldof
materials, since itdefinitelyverifies that the filmgrowthproceeds in
layer-by-layermodewitheach layer thicknesscontrollableby simply
counting thenumberofoscillations.Thisenabled the fabricationof
nano-engineeredhetero-junctionsanddevicesascommonlypracticed
forconventionalsemiconductorsandmetals.Herewereportonthefirst
observationofclearRHEEDintensityoscillationinthinfilmfabricationof
aπ-conjugatedmolecularsolid.Theobservationhasbeenachievedby
couplinganoveldepositionmethodusingacontinuous-wave infrared
laserforevaporationandahighsensitiveRHEEDdetector,inadditionto
thecombinatorialoptimizationoffilmdepositionparametersthatfacili-
tatedourprecedingfirstsuccess inthe layer-by-layergrowthofoxide
thinfilms.Somedetailsofsystemdesignandexperimentalconditionsare
presentedtodiscussthekeyfactorsforatomicallycontrolledfilmgrowth
ofmolecularsolids.[DOI:10.1143/APEX.1.015005]
1 MaterialsandStructuresLaboratory,TokyoInstituteofTechnology,4259Nagatsuta,Midori-ku,Yokohama226-8503,Japan
2 GraduateSchoolofFrontierSciences,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8568,Japan
3 CREST,JapanScienceandTechnologyAgency(JST),4-1-8Honcho,Kawaguchi,Saitama332-0012,Japan
4 NationalInstituteforMaterialsScience,1-2-1Sengen,Tsukuba,Ibaraki305-0047,Japan5 DepartmentofChemistry,SaitamaUniversity,255Shimo-Okubo,Sakura-ku,Saitama
338-8570,Japan6 InstituteforSolidStatePhysics,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,
Chiba277-8581,Japan* E-mailaddress:koinuma@k.u-tokyo.ac.jp
Appl. Phys. Express Vol.1, No.1 (2008) 015006
Selective-Area Growth of GaN Nanocolumns on Si(���) Substrates Using Nitrided Al Nanopatterns by RF-Plasma-Assisted Molecular-Beam EpitaxyShunsukeIshizawa1,2,KatsumiKishino1,2,*,andAkihikoKikuchi1,2
(ReceivedDecember5,2007;acceptedDecember9,2007;publishedonlineJanuary17,2008)
Theselective-areagrowthofGaNnanocolumnsusingpredeposited
Alnanopatterns(a300-nm-periodtriangular latticeof85-nm-diameter
Alnanodots)onSi(111)substratesbyrf-plasma-assistedmolecular-beam
epitaxy(rf-MBE)wasdemonstrated.GaNnanocolumnsweregrownat
theedgeofeachnitridedAldotafternitridation,formingananotubular
structure in thegrowth temperature range from941to966°C.The
sizefluctuationof thesidewall thickness in thenanotubularstructure
was lessthanthatofthediametersofnanocolumnsgrownontheSi
surfaceoutsidethenitridedAlnanopatterns.Atahighgrowthtempera-
tureof966°C,nanocolumngrowthontheSisurfacewascompletely
suppressed.[DOI:10.1143/APEX.1.015006]
1 DepartmentofElectricalandElectronicsEngineering,SophiaUniversity,Tokyo102-8554,Japan
2 CREST,JapanScienceandTechnologyAgency,Saitama332-0021,Japan* E-mailaddress:kishino@katsumi.ee.sophia.ac.jp
�0JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.2 (2008) 021102
Improvement of Al-Polar AlN Layer Quality by Three-Stage Flow-Modulation Metalorganic Chemical Vapor DepositionMisaichiTakeuchi1,2,3,*,ShinOoishi2,TakumiOhtsuka2,TomohiroMaegawa2,TakahiroKoyama4,ShigefusaF.Chichibu4,andYoshinobuAoyagi1,2,3
(ReceivedDecember10,2007;acceptedJanuary9,2008;publishedonlineFebruary1,2008)
ImprovementofAl-polarAlN layerqualitywasaccomplishedby
three-stage flow-modulationmetalorganicchemicalvapordeposition
(FM-MOCVD).Inthismethod,theunitoftheFM-MOCVDsequencewas
composedofthreestages;StageIforsimultaneoussourcesupply,Stage
IIfortrimethylaluminumsupply,andStageIIIforammoniasupply,which
werecyclicallyrepeated.TheAlNqualityrevealedbyX-raydiffraction
stronglydependedonthetimeofStageI.Agrowthmodelwasproposed
consideringthesurfacecoverageoftheislandsnucleatedduringStage
I.Excitonfinestructureswereeventuallyobservedby low-temperature
cathodoluminescencereflectingthetremendously improvedcrystalline
quality.[DOI:10.1143/APEX.1.021102]
1 NanoscienceDevelopmentandSupportTeam,RIKEN,2-1Hirosawa,Wako,Saitama351-0198,Japan
2 DepartmentofElectronicsandAppliedPhysics,TokyoInstituteofTechnology,4259Nagatsuta,Midori-ku,Yokohama226-8503,Japan
3 RitsumeikanUniversity,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,Japan4 CenterforAdvancedNitrideTechnology(CANTech),InstituteofMultidisciplinaryResearch
forAdvancedMaterials(IMRAM),TohokuUniversity,2-1-1Katahira,Aoba,Sendai980-8577,Japan
* E-mailaddress:Misa.Takeuchi@riken.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021103
AlGaN/GaN Heterostructure Field-Effect Transistors on �H-SiC Substrates with Current-Gain Cutoff Frequency of ��0GHzMasatakaHigashiwaki1,*,TakashiMimura1,2,andToshiakiMatsui1(ReceivedDecember26,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)
We reporton state-of-the-artAlGaN/GaNheterostructure field-
effecttransistor(HFET)technologyinthescopeofmillimeter-waveappli-
cations.60-nm-long-gateHFETshaving4-and6-nm-thickAl0.4Ga0.6N
barrier layersandSiNpassivation layers formedbycatalyticchemical
vapordeposition(Cat-CVD)werefabricatedon4H-SiCsubstrates.Both
structureshadlowsheetresistancesof200–220Ω / sqthatweredueto
notonlyhighmobilitiesof1900–2000cm2/(V·s)butalsohighelectron
densitiesof (1.4–1.7)×1013cm-2,whichwereprovidedbythehigh-Al-
compositionbarrierlayersandtheCat-CVDSiN.Thedeviceswiththe4-
and6-nm-thickbarriershadmaximumdraincurrentdensitiesof1.4and
1.6A/mmandpeakextrinsictransconductancesof448and424mS/mm,
respectively.MaximumfTandfmax reached190and251GHz,respec-
tively.[DOI:10.1143/APEX.1.021103]
1 NationalInstituteofInformationandCommunicationsTechnology,4-2-1Nukui-Kitamachi,Koganei,Tokyo184-8795,Japan
2 FujitsuLaboratoriesLtd.,10-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0197,Japan* Presentaddress:DepartmentofElectricalandComputerEngineering,Universityof
California,SantaBarbara,SantaBarbara,CA93106,U.S.A. E-mailaddress:mhigashi@ece.ucsb.edu
Appl. Phys. Express Vol.1, No.1 (2008) 015007
Thermal Stability of Giant Thermoelectric Seebeck Coefficient for SrTiO�/SrTi0.�Nb0.�O� Superlattices at �00KKyuHyoungLee1,*,YorikoMune2,HiromichiOhta1,2,**,andKunihitoKoumoto1,2
(ReceivedDecember5,2007;acceptedDecember15,2007;publishedonlineJanuary17,2008)
Hereinwe report thecarrier transportpropertiesof [(SrTiO3)x /
(SrTi0.8Nb0.2O3)1]20(x=0–50)superlatticesathightemperatures(T=300–
900K).Significantstructuralchangeswerenotobservedinthesuperlat-
ticesafterannealingat900Kinavacuum.TheSeebeckcoefficientof
the [(SrTiO3)20 / (SrTi0.8Nb0.2O3)1]20 superlattice,whichwas300µV·K-1
at room temperature, gradually increased with temperature and
reached450µV·K-1at900K,whichis~3timeslargerthanthatofbulk
SrTi0.8Nb0.2O3.Theseobservationsprovideclearevidencethatthesuper-
lattice is stableandexhibitsagiantSeebeckcoefficientevenathigh
temperature.[DOI:10.1143/APEX.1.015007]
1 CREST,JapanScienceandTechnologyAgency,4-1-8Honcho,Kawaguchi,Saitama332-0012,Japan
2 GraduateSchoolofEngineering,NagoyaUniversity,Furo-cho,Chikusa,Nagoya464-8603,Japan
* Presentaddress:AdvancedMaterialsLaboratory,SamsungAdvancedInstituteofTechnology,P.O.Box111,Suwon,Korea.
**E-mailaddress:h-ohta@apchem.nagoya-u.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021101
Study on Injection Efficiency in InGaN/GaN Multiple Quantum Wells Blue Light Emitting DiodesLaiWang,JiaxingWang,HongtaoLi,GuangyiXi,YangJiang,WeiZhao,YanjunHan,andYiLuo*
(ReceivedDecember6,2007;acceptedDecember28,2007;publishedonlineJanuary25,2008)
Thedependenceoftheelectricalefficiencyontheinjectioncurrent
wasstudiedindetailinInGaN/GaNmultiplequantumwells(MQWs)blue
lightemittingdiodes.WhentheInGaNquantumwellthicknessincreased
from2to3.5nm,ortheAlcomponent inp-AlGaNchangedfrom0.1
to0.2,itwasfoundthattheelectricalefficiencydecreaseddramatically,
whileathinMg-dopedGaNlayerinsertedbetweenp-AlGaNandMQWs
withoptimizedMgconcentrationcanenhancetheelectricalefficiency
effectively.Analysisshowsthattheinjectionefficiencywasdramatically
affectedbytheinterfacestatesduetothestrongstressattheinterface
betweenp-AlGaNblockinglayerandMQWsactiveregionandthecapa-
bilityofelectronsarrivingattheinterface.
[DOI:10.1143/APEX.1.021101]
StateKeyLaboratoryonIntegratedOptoelectronics/TsinghuaNationalLaboratoryforInformationScienceandTechnology,DepartmentofElectronicEngineering,TsinghuaUniversity,Beijing100084,P.R.China* E-mailaddress:luoy@tsinghua.edu.cn
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.2 (2008) 021104
GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistor Fabricated with Novel Wet EtchingMasahitoKodama*,MasahiroSugimoto1,EikoHayashi,NarumasaSoejima,OsamuIshiguro,MasakazuKanechika,KenjiItoh,HiroyukiUeda,TsutomuUesugi,andTetsuKachi(ReceivedDecember21,2007;acceptedJanuary24,2008;publishedonlineFebruary15,2008)
Anovelmethod for fabricating trench structuresonGaNwas
developed.A smoothnon-polar (11–00)planewasobtainedbywet
etchingusingtetramethylammoniumhydroxide(TMAH)astheetchant.
AU-shape trenchwith the (11–00)planesidewallswas formedwith
dryetchingandtheTMAHwetetching.AU-shapetrenchgatemetal
oxidesemiconductor field-effect transistor (MOSFET)wasalso fabri-
catedusingthenoveletchingtechnology.Thisdevicehastheexcellent
normally-offoperationofdraincurrent–gatevoltagecharacteristicswith
the thresholdvoltageof10V.Thedrainbreakdownvoltageof180V
wasobtained.Theresultsindicatethatthetrenchgatestructurecanbe
appliedtoGaN-basedtransistors.[DOI:10.1143/APEX.1.021104]
ToyotaCentralR&DLaboratories,Inc.,Nagakute-cho,Aichi480-1192,Japan1 ToyotaMotorCorp.,543Kirigahora,Nishihirose-cho,Toyota,Aichi470-0309,Japan* E-mailaddress:kodama@mosk.tytlabs.co.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021201
Epitaxial Lift-Off of InGaAs/InAlAs Metamorphic High Electron Mobility Heterostructures and Their van der Waals Bonding on AlN Ceramic SubstratesYonkilJeong,MasanoriShindo,MasashiAkabori*,andToshi-kazuSuzuki**
(ReceivedNovember28,2007;acceptedDecember24,2007;publishedonlineJanuary25,2008)
Wehave carried out epitaxial lift-off (ELO) of In0.57Ga0.43As/
In0.56Al0.44Asmetamorphichighelectronmobilityheterostructuresand
theirvanderWaalsbonding (VWB)onAlNceramicsubstrates.Using
ametamorphicheterostructurewithanAlAssacrificial layerandan
InGaAsgradedbuffergrownonGaAs(001), thinfilmHall-bardevices
onAlNceramic substrateswere successfully fabricatedbyELOand
VWB.TheHall-bardevicesexhibitveryhighelectronmobilities,suchas
11000cm2/(Vs)atroomtemperature (RT)and84000cm2/(Vs)at12K.
TheRTmobilityisthehighesteverreportedforELOdevices.Thisisthe
firstreportonELOformetamorphicdevices.
[DOI:10.1143/APEX.1.021201]
CenterforNanoMaterialsandTechnology,JapanAdvancedInstituteofScienceandTechnology(JAIST),1-1Asahidai,Nomi,Ishikawa923-1292,Japan* Presentaddress:InstituteofBio-andNanosystems(IBN-1),ResearchCentreJuelich,52425
Juelich,Germany.**E-mailaddress:tosikazu@jaist.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021301
Tunnel Magnetoresistance Effect in Magnetic Tunnel Junctions Using a Co�MnSi(��0) ElectrodeMasashiHattori,YuyaSakuraba,MikihikoOogane,YasuoAndo,andTerunobuMiyazaki(ReceivedDecember20,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)
Magnetic tunnel junctions (MTJs)withhalf-metallic electrodes
areexpected toshowa large tunnelmagnetoresistance (TMR) ratio,
accordingtoJulliere'smodel.ACo2MnSiHeusleralloy is theoretically
expectedtopossessahalf-metallicelectronicstate.Experimentally,at
low temperature,Co2MnSi(100)/Al-oxide/CoFe junctionsexhibiteda
largeTMRratio.WefabricatedMTJswithhigh-quality (110)-oriented
Co2MnSielectrodesand investigatedtheTMReffects.Weobtaineda
TMRratioofabout40%atroomtemperatureand120%at2K,respec-
tively.However,weobserveddegradationoftheenergygapofCo2MnSi
intheminorityspinbandfromtheconductance–voltagecharacteristics.
WeinferthattheinterfaceofCo2MnSi(110)possessesnohalf-metallic
property.[DOI:10.1143/APEX.1.021301]
DepartmentofAppliedPhysics,GraduateSchoolofEngineering,TohokuUniversity,Aoba-ku,Sendai980-8579,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 021302
Enhanced Interlayer Coupling and Magnetoresistance Ratio in Fe�Si/FeSi� SuperlatticesKaoruTakeda,TsuyoshiYoshitake*,YoshikiSakamoto,TetsuyaOgawa,DaisukeHara,MasaruItakura,NoriyukiKuwano,ToshinoriKajiwara1,andKunihitoNagayama2
(ReceivedJanuary8,2008;acceptedJanuary18,2008;publishedonlineFebruary8,2008)
[Fe3Si / FeSi2]20superlatticeswerepreparedonSi(111)atanelevated
substratetemperatureof300°C,andthemagnetoresistanceratioand
interlayercouplingstrengthswereenhancedbyapproximately100and
34%,respectively,ascomparedtothoseofsuperlatticesdepositedat
roomtemperature.Whiletheelevatedsubstratetemperaturedegraded
theinterfacesharpness,thecrystallineorientationandthecrystallinityof
theFe3Silayerswereapparentlyenhanced.Thelattersstronglyinfluence
ontheinterlayercouplingandthemagnetoresistanceratio.Thisimplies
thatquantumwellstatesaretightlyformedunderthewell-orderedcrys-
tallineplanes,andthespindiffusion lengthsare improvedduetothe
enhancedcrystallinity.[DOI:10.1143/APEX.1.021302]
DepartmentofAppliedScienceforElectronicsandMaterials,KyushuUniversity,6-1Kasuga,Fukuoka816-8580,Japan1 DepartmentofElectricalEngineering,FukuokaInstituteofTechnology,Higashi-ku,Fukuoka
811-0295,Japan2 DepartmentofAeronautics,KyushuUniversity,Nishi-ku,Fukuoka819-0395,Japan* E-mailaddress:yoshitake@asem.kyushu-u.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.2 (2008) 021401
Quantitative Evaluation of Silicon Displacement Induced by Arsenic Implantation Using Silicon Isotope SuperlatticesYasuoShimizu,MasashiUematsu,KoheiM.Itoh*,AkioTakano1,KentarouSawano2,andYasuhiroShiraki2(ReceivedNovember21,2007;acceptedDecember28,2007;publishedonlineJanuary25,2008)
Weestablishedanewmethod forevaluatingquantitatively the
siliconatomicdisplacementasafunctionofthedepthfromthesurface
inducedbyarsenicimplantationintoasiliconwafer.Asimulationbased
onaconvolutionintegralwasdevelopedsuccessfullytoreproducethe
experimentaldepthprofilesofisotopesinthearsenic-implanted28Si / 30Si
isotopesuperlattices, fromwhich theaveragedistanceof thesilicon
displacementsduetothecollisionswith implantedarsenic isobtained.
Weshowthatittakestheaveragedisplacementof~0.5nmtomakethe
structureappearamorphousbytransmissionelectronmicroscopy.
[DOI:10.1143/APEX.1.021401]
DepartmentofAppliedPhysicsandPhysico-Informatics,KeioUniversity,3-14-1Hiyoshi,Kohoku-ku,Yokohama223-8522,Japan1 NTTAdvancedTechnologyCorporation,3-1Morinosato-Wakamiya,Atsugi,Kanagawa
243-0124,Japan2 ResearchCenterforSiliconNano-Science,AdvancedResearchLaboratories,Musashi
InstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan* E-mailaddress:kitoh@appi.keio.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021402
Room-temperature Transport Properties of High Drift Mobility Two-dimensional Electron Gas Confined in a Strained Si Quantum WellMaksymMyronov,KentarouSawano,KoheiM.Itoh1,andYasuhiroShiraki(ReceivedDecember1,2007;acceptedDecember18,2007;publishedonlineJanuary25,2008)
Thedriftmobility,carrierdensityandconductivityofthetwo-dimen-
sionalelectrongas (2DEG)confined in the tensilelystrained15nmSi
quantumwell(QW)ofSiGeheterostructureswereobtainedbymobility
spectrumanalysisatroom-temperature.Thehighest2DEGdriftmobility
of2900cm2V-1s-1withcarrierdensityof1×1011cm-2wereobserved
intheSiQWwith-0.9%tensilestrain.However,theincreaseofstrain
upto-1.08%resulted inthedeclineof2DEGdriftmobilitydownto
2670cm2,V-1s-1andthepronounced increaseofcarrierdensityupto
4.4×1011cm-2.Nevertheless, thepronouncedenhancementof2DEG
conductivitywasobserved.[DOI:10.1143/APEX.1.021402]
AdvancedResearchLaboratories,MusashiInstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan1 DepartmentofAppliedPhysicsandPhysico-Informatics,KeioUniversity,Yokohama
223-8522,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 021403
Improved Room-Temperature �.�µm Electroluminescence from p-Si/β-FeSi�/n-Si Double Heterostructures Light-Emitting DiodesMitsushiSuzuno,ShigemitsuMurase,TomoakiKoizumi,andTakashiSuemasu(ReceivedJanuary21,2008;acceptedJanuary27,2008;publishedonlineFebruary15,2008)
Wehaveepitaxiallygrownp-Si /β-FeSi2 /n-Sidoubleheterostructures
light-emittingdiodes (LEDs)onSi(111)substratesbymolecular-beam
epitaxy.The1.6µmelectroluminescence intensitymeasuredat room
temperature(RT)wasimprovedsignificantlyforLEDsconstructedusing
athickβ-FeSi2activelayer(190nm)embeddedinheavily-dopedSip–n
diodesformedonfloating-zoneSi(111)substrates.Theexternalquantum
efficiencywasincreaseduptoapproximately0.02%atRT.
[DOI:10.1143/APEX.1.021403]
InstituteofAppliedPhysics,UniversityofTsukuba,1-1-1Tennohdai,Tsukuba,Ibaraki305-8573,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 021501
Un-stability of Sputtered Ge�Sb�Te� Films in Electrical Phase ChangesAkiraSaitoh,ToshiakiDonuma,andKeijiTanaka(ReceivedDecember11,2007;acceptedDecember22,2007;publishedonlineJanuary25,2008)
MicroscopicstructuresofamorphousGe2Sb2Te5 films,electrically
phase-changedusingco-planarelectrodes,havebeenstudiedthrough
electricalandstructuralinvestigations.Microscopeimagesshowastruc-
turedphase-changeregionconsistingofanarrowchannel,bankson
bothsides,androughperipheralregions.Theroom-temperatureresis-
tivity is~10-3Ω·cm,whichhasametallic temperaturedependence.
Micro-Ramanscatteringspectraat thechanneland thebankexhibit
peaksduetocrystallineTeandtellurides.X-raydiffractionpatternsfrom
thefilms,whichcontainmanychannels,presentcrystallinepeaksascrib-
abletocubicGeTeandothercompounds.Theseobservationssuggest
thattheGe2Sb2Te5meltisliabletophase-separateunderelectricalself-
heating.[DOI:10.1143/APEX.1.021501]
DepartmentofAppliedPhysics,GraduateSchoolofEngineering,HokkaidoUniversity,Sapporo060-8628,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 021701
Improvement of Superconductive Properties of Mesoscopic Nb Wires by Ti Passivation LayersKoheiOhnishi1,TakashiKimura1,2,andYoshichikaOtani1,2
(ReceivedDecember17,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)
Wehave investigated superconductivepropertiesofnano-scale
Nbwires fabricatedbyasimple lift-offprocesswithmagnetronsput-
tering.Thesuperconductivepropertiesof theNbwireswereremark-
ablyimprovedbyemployinghighlyplasmaresistantelectron-beamresist
ZEP520AcombinedwithathinTipassivationlayer.Thisoptimizedfabri-
cationprocessyieldeda300-nm-wideNbwirewiththesametransition
temperatureasthatofthereferenceNbfilm.Thereby,ahighlytrans-
parentNb/Cujunctionwassuccessfullyfabricated.
[DOI:10.1143/APEX.1.021701]
1 InstituteforSolidStatePhysics,UniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8581,Japan
2 FrontierResearchSystem,RIKEN,2-1Hirosawa,Wako,Saitama351-0198,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.2 (2008) 021702
MgB� Thin Films Fabricated by a Precursor and Post-annealing Method Have a High Jc in High Magnetic FieldsAkiyoshiMatsumoto,YukiKobayashi,Ken-ichiroTakahashi,HiroakiKumakura,andHitoshiKitaguchi(ReceivedDecember26,2007;acceptedJanuary15,2008;publishedonlineFebruary1,2008)
Thecriticalcurrentdensities (Jc)ofMgB2 thin filmsdepositedon
α-Al2O3fabricatedbyaprecursorandpost-annealingprocesshavebeen
investigatedinhighmagneticfieldsofupto30T.Jcvaluesof2.8×105,
3.0×104,and3.7×103A/cm2wereobtainedat4.2Kinexternalmagnetic
fieldsof10,20,and26Trespectively,appliedparalleltothefilmsurface.
ThesevalueswerecomparabletothoseseenforNb3Sninfieldsupto
18T,andsurpassedtheminfieldsover18T.Thesuperconductingtran-
sitiontemperaturewasTconset=29.6KandTc
zero=28.5K.Grainconnec-
tivitywasestimatedtobe38.4%.TheHc2(0)estimatedfromtheresis-
tivitymeasurementswas45T.Transmissionelectronmicroscope(TEM)
observationsof themicrostructuressuggested thatgrains10 –20nm
insizeexistthatshownoepitaxialgrowthrelationshiptothesapphire
substrate.Jcenhancements infieldsupto~26Tareduetothestrong
grainboundarypinningassociatedwiththesmallgrainsandthesmall
sizeofMgOprecipitates.[DOI:10.1143/APEX.1.021702]
NationalInstituteforMaterialsScience,1-2-1Sengen,Tsukuba,Ibaraki305-0047,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 021801
Characterization of Depletion Layer using Photoluminescence TechniqueVipulSingh*,AnilK.Thakur,ShyamS.Pandey,WataruTakashima,andKeiichiKaneto(ReceivedNovember19,2007;acceptedDecember18,2007;publishedonlineJanuary25,2008)
Thedepletionlayerformedatthe interfaceofaluminum(Al)with
poly(3-hexylthiophene-2,5-diyl)(P3HT)hasbeenstudied,usingthebias
dependentphotoluminescence (PL) spectra in indiumtinoxide (ITO)/
P3HT/Al sandwichedcells.Aquenching in thePL intensityhasbeen
observedunderthereversebiasconditions,whichhasbeenattributedto
theincreaseinthedepletionlayerwidth.Adirectrelationshipbetween
thedepletionlayerwidthandthePLquenchinghasbeenderivedand
explained.[DOI:10.1143/APEX.1.021801]
GraduateSchoolofLifeSciencesandSystemsEngineering,KyushuInstituteofTechnology,2-4Hibikino,Wakamatsu-ku,Kitakyushu808-0196,Japan* E-mailaddress:vipulsingh79@gmail.com
Appl. Phys. Express Vol.1, No.2 (2008) 021802
Improvement of Hole Mobility in Organic Field-Effect Transistors Based on Octyl-substituted Oligo-p-phenylenevinylene by Thermal Treatment at Smectic Liquid Crystalline PhaseHiroakiNakamura*,MasatoshiSaito,TadashiKusumoto,TakeshiYasuda1,2,andTetsuoTsutsui1(ReceivedDecember7,2007;acceptedDecember15,2007;publishedonlineJanuary25,2008)
Organicfield-effecttransistorsbasedonoctyl-subustitutedoligo-p-
phenylenevinylenehavebeenstudied.Wehavesucceededinimproving
field-effectholemobilitiesbythermaltreatmentatliquidcrystallinephase
characterizedasahighlyorderedsmecticphase.Thefield-effectmobility
ofthedeviceasvacuum-evaporatedwascalculatedtobe6.9×10-3cm2
V-1s-1whereasthemobilitywasenhancedto1.7×10-1cm2V-1s-1after
annealingthedeviceat100°Cfor12h.Fromthesurfacemorphology
ofthefilmsobservedbyusingatomicforcemicroscope,theenhance-
mentisfoundtobeattributedtoreductionofdefectdensityinthefilm
becauseof the thermalmovementof liquid-crystalmolecules. [DOI :
10.1143/APEX.1.021802]
CentralResearchLaboratories,IdemitsuKosanCo.,Ltd.,Sodegaura,Chiba299-0293,Japan1 DepartmentofAppliedScienceforElectronicsandMaterials,GraduateSchoolof
EngineeringSciencesandInstituteforMaterialChemistryandEngineering,KyushuUniversity,Kasuga,Fukuoka816-8580,Japan
2 PRESTO,JapanScienceandTechnologyAgency,Chiyoda-ku,Tokyo102-0075,Japan* E-mailaddress:hiroaki.nakamura@si.idemitsu.co.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021803
Complementary Two-input NAND Gates with Low-voltage-operating Organic Transistors on Plastic SubstratesJongHoNa1,*,MasatoshiKitamura2,andYasuhikoArakawa1,2
(ReceivedNovember19,2007;acceptedJanuary9,2008;publishedonlineFebruary1,2008)
Wefabricatedtwo-inputNANDgatescomposedofp-channelpenta-
ceneandn-channelC60transistors.Thelogicdeviceswerepreparedon
flexiblepolymersubstrates throughashadowmaskprocess.Correct
NAND logic functionalitywasdemonstratedatawidevoltagerange
of2–7V.FromvoltagetransfercharacteristicsoftheNANDgates,we
obtainedimpressivesignalgainsupto120andlargenoisemargins in
thegivenvoltagerange.[DOI:10.1143/APEX.1.021803]
1 ResearchCenterforAdvancedScienceandTechnology,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan
2 InstituteforNanoQuantumInformationElectronics,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan
* E-mailaddress:pions@iis.u-tokyo.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.2 (2008) 021804
Whitening of Polymer Light-Emitting Diodes by Dispersing Vapor of an Orange Fluorescent Dye into a Blue-Emitting Polymer FilmToshikoMizokuro*,ClaireHeck,NobutakaTanigaki,TakashiHiraga,andNorioTanaka1
(ReceivedDecember28,2007;acceptedJanuary11,2008;publishedonlineFebruary1,2008)
Whiteningofpolymer light-emittingdiodes (PLEDs)basedonthe
blue-emittingpoly(9,9-dioctylfluorene) (PDOF) filmswaspossibleby
dispersingvaporofanorangefluorescentdye4-(dicyanomethylene)-
2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) into the filmby
meansofthesolution-freevaportransportationmethod(VTM).Devices
preparedwiththismethodshowedgoodcolorstabilitywithbiasvoltage
increase,whilethoseformedwithconventionalspin-coating,wheredyes
andpolymersweremixedinasolution(solution-mixed),showedcolor
changefromyellowtowhite-yellow.Themaximumluminanceof the
PLEDformedbytheVTMwashigherthanthatformedbyconventional
spin-coatingprocess.[DOI:10.1143/APEX.1.021804]
PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology,1-8-31Midorigaoka,Ikeda,Osaka563-8577,Japan1 DainichiseikaColorandChemicalsManufacturingCo.,Ltd.,1-9-4Horinouchi,Adachi-ku,
Tokyo123-8555,Japan* E-mailaddress:chem42@ni.aist.go.jp
Appl. Phys. Express Vol.1, No.2 (2008) 021805
Highly Efficient Phosphorescent Organic Light-Emitting Diodes Using Alkyl-Substituted Iridium Complexes as a Solution-Processible Host MaterialToshimitsuTsuzuki*andShizuoTokito(ReceivedJanuary11,2008;acceptedJanuary24,2008;publishedonlineFebruary15,2008)
Wefabricatedhighlyefficientorganic light-emittingdiodes(OLEDs)
usingthesolutionprocessible iridiumcomplexeswhichhavelongalkyl
orcycloalkylsubstituentsinanancillaryligandasahostmaterialanda
redphosphorescentiridiumcomplexasanemittingguestbyspincoating
method.TheOLEDsemittedredphosphorescencefromtheguestand
theluminancereachedaround10,000cd/m2.TheefficiencyoftheOLED
improvedafterweaddedanelectrontransportmaterial (ETM)tothe
emittinglayer.TheOLEDusingamixtureofthealkylsubstitutediridium
complexandETMasthehostshowedanexternalquantumefficiencyof
10%.[DOI:10.1143/APEX.1.021805]
ScienceandTechnicalResearchLaboratories,NHK,Setagaya-ku,Tokyo157-8510,Japan* E-mailaddress:tsuzuki.t-hq@nhk.or.jp
Appl. Phys. Express Vol.1, No.2 (2008) 022001
Waveguide-Integrated Si Nano-Photodiode with Surface-Plasmon Antenna and its Application to On-chip Optical Clock DistributionJunichiFujikata*,KoichiNose,JunUshida,KenichiNishi,MasaoKinoshita,TakanoriShimizu,ToshihideUeno,DaisukeOkamoto,AkikoGomyo,MasayukiMizuno,TaiTsuchizawa1,ToshifumiWatanabe1,KojiYamada1,SeiichiItabashi1,andKeishiOhashi(ReceivedNovember21,2007;acceptedDecember24,2007;publishedonlineJanuary25,2008)
Wedevelopedawaveguide-integratedSinano-photodiode(PD)with
asurfaceplasmon(SP)antennaforon-chipopticalclockdistribution.The
interfacialperiodicnano-scalemetal – semiconductor –metalSchottky
electrodeswereshowntofunctionasanSPopticalantennaandalsoas
anopticalcouplerbetweenaSiONwaveguideandaverythinSi-absorp-
tionlayer.Furthermore,averyhighspeedresponseof17psaswellas
enhancedphotoresponsivitywasachievedfora10-µmcouplinglength.
Byusingthis technology,wefabricatedaprototypeofa large-scale-
integration(LSI)on-chipopticalclocksystemanddemonstrated5GHzof
opticalclockcircuitoperationconnectedwitha4-branchingH-treestruc-
ture.[DOI:10.1143/APEX.1.022001]
MIRAI-Selete,34Miyukigaoka,Tsukuba,Ibaraki305-8501,Japan1 NTTMicrosystemIntegrationLabs.,3-1Morinosato-Wakamiya,Atsugi,Kanagawa
243-0198,Japan* E-mailaddress:fujikata.jyunichi@selete.co.jp
Appl. Phys. Express Vol.1, No.2 (2008) 022002
Semiconductor Waveguide Optical Isolator Incorporating Ferromagnetic Epitaxial MnSb for High Temperature OperationTomohiroAmemiya*,YusukeOgawa1,HiromasaShimizu2,HiroMunekata1,andYoshiakiNakano**
(ReceivedNovember26,2007;acceptedDecember9,2007;publishedonlineJanuary25,2008)
A1.5-µmnonreciprocal-losswaveguideoptical isolatorhaving
improved transverse-magnetic-mode (TM-mode) isolation ratiowas
developed.Thedeviceconsistedofan InGaAlAs/InP semiconductor
opticalamplifierwaveguidecoveredwithaferromagneticepitaxialMnSb
layer.BecauseofthehighCurietemperature(Tc=314°C)andstrong
magneto-optical effectofMnSb, thenonreciprocalpropagationof
11–12dB/mmhasbeenobtainedatleastupto70°C.
[DOI:10.1143/APEX.1.022002]
ResearchCenterforAdvancedScienceandTechnology,TheUniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan1 ImagingScienceandEngineeringLaboratory,TokyoInstituteofTechnology,4259-G2-13
Nagatsuta,Midori-ku,Yokohama226-8502,Japan2 DepartmentofElectricalandElectronicEngineering,TokyoUniversityofAgricultureand
Technology,2-24-16Nakacho,Koganei,Tokyo184-8588,Japan* E-mailaddress:ametomo@hotaka.t.u-tokyo.ac.jp**E-mailaddress:nakano@ee.t.u-tokyo.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.2 (2008) 022003
New Precise Fabrication Technology for Lenticular Lens Sheet with Black Stripe Patterns by Using Photo-Sensitive Material with Surface ModifierAtsushiNagasawa*,KatsuyaFujisawa1,andToshiyukiWatanabe2
(ReceivedDecember6,2007;acceptedDecember22,2007;publishedonlineJanuary25,2008)
Wehavedevelopedanewprecise fabrication technologyofa
lenticularlenssheetwithblackstripepatternsforarear-projectiontele-
vision.Theblackstripepatternshavetobeaccuratelyalignedtocylin-
dricallensesonthelenticularlenssheetandbeabletoabsorbambient
light.Ourproposedtechnologyutilizedaphoto-sensitivematerialwitha
surfacemodifierwhichcontrolssurfacefreeenergyforsurfacemodifica-
tion.Usingthismaterial,wecouldobtaintwopatternedareaswhichhad
differentsurfacefreeenergies.Furthermore,fabricationofblackstripe
patternsonthelenticularlenssheetwascarriedoutbyaself-alignment
method.This lenticular lenssheetwithblackstripepatternshadsimilar
opticalpropertiescomparedwithaconventionalone.
[DOI:10.1143/APEX.1.022003]
TechnologyResearchAssociationforAdvancedDisplayMaterials(TRADIM),2-24-16Nakamachi,Koganei,Tokyo184-0012,Japan1 KurarayCo.,Ltd.,41Miyukigaoka,Tsukuba,Ibaraki305-0841,Japan2 DepartmentofOrganicandPolymerMaterialsChemistry,TokyoUniversityofAgriculture
andTechnology,2-24-16Nakamachi,Koganei,Tokyo184-0012,Japan* E-mailaddress:a.nagasawa@tradim.or.jp
Appl. Phys. Express Vol.1, No.2 (2008) 022004
Single-Mode Vertical-Cavity Surface-Emitting Lasers with a Deep-Etched Half-Ring-Shaped Holey StructureHung-PinD.Yang,Fang-ILai1,andJimY.Chi(ReceivedDecember10,2007;acceptedJanuary5,2008;publishedonlineJanuary25,2008)
Asingle-modeoxide-confinedvertical-cavitysurface-emitting laser
(VCSEL)withdeeply-etchedhalf-ring-shapedholeystructurefor fiber-
opticapplications isdemonstrated.Single fundamentalmodecontin-
uous-waveoutputpowerof2.6mWhasbeenachievedinthe850nm
range,witha thresholdcurrentofapproximately1mA.Side-mode
suppressionratio(SMSR)largerthan26dBhasbeenmeasured.Contrary
to thepreviously reported surface reliefmethods, thedeep-etched
(approximately2.2µmindepth)holeystructure inthispaperprovides
anotherapproachtoachievesingle-modeoperationoftheVCSELwitha
largeroxideaperture.[DOI:10.1143/APEX.1.022004]
ElectronicsandOptoelectronicsResearchLaboratories,IndustrialTechnologyResearchInstitute,Chutung31015,Hsinchu,Taiwan31015,R.O.C.1 DepartmentofElectricalEngineering,YuanZeUniversity,Chung-Li,Taiwan32003,R.O.C.
Appl. Phys. Express Vol.1, No.2 (2008) 022005
Generation of Periodic Sawtooth Optical Intensity by Phase-Shifting MaskShogoUra*,KenjiKintaka1,HideyukiAwazu,KenzoNishio,YasuhiroAwatsuji,andJunjiNishii2(ReceivedDecember19,2007;acceptedJanuary11,2008;publishedonlineFebruary1,2008)
Anewsimpleinterferenceexposuremethodusingaphase-shifting
maskwasdiscussedon thebasisofFourier synthesis for fabricating
blazedgratings.Phase-shiftingmaskwasdesignedwith244nmexpo-
sure-lightwavelengthtolaunchmultiplediffractionbeamssothatresul-
tant interferencepattern fit to requiredoptical intensityprofile.Fine
surface-reliefpatternonSiO2maskfor3-µm-periodsawtoothoptical-
intensityprofilewasfabricatedbyelectron-beamdirect-writing lithog-
raphywith30nmscanningstepandreliefheightof65nm.Sawtooth-
like intensityprofilewasdemonstratedwith theoreticallypredicted
interferencevisibility.[DOI:10.1143/APEX.1.022005]
DepartmentofElectronics,GraduateSchoolofScienceandTechnology,KyotoInstituteofTechnology,Kyoto606-8585,Japan1 PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand
Technology,Tsukuba,Ibaraki305-8568,Japan2 PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand
Technology,Ikeda,Osaka563-8577,Japan* E-mailaddress:ura@kit.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 022006
Three-Dimensional Profiling of Refractive Index Distribution inside Transparent Materials by Use of Nonresonant Four-Wave Mixing MicroscopyKeisukeIsobe,TakehitoKawasumi,TakayukiTamaki,ShogoKataoka,YasuyukiOzeki,andKazuyoshiItoh(ReceivedDecember10,2007;acceptedJanuary15,2008;publishedonlineFebruary8,2008)
Wepropose that four-wavemixing (FWM)microscopy canbe
appliedtothree-dimensionalmappingofrefractive index(RI)structure
insidetransparentsamples.Wederiveananalyticalrelationshipbetween
theRIand the intensityof theFWMsignal that isdue tononreso-
nantopticalnonlinearity.Byusingtherelationship,theRIprofilecanbe
directlyandquantitativelyobtainedfromtheintensitydistributionofthe
FWMsignal.WeexperimentallydemonstratetheRIprofilingofaphase
gratingfabricatedinanon-alkaliglass.
[DOI:10.1143/APEX.1.022006]
DepartmentofMaterialandLifeScience,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.2 (2008) 022007
Generation of High Efficiency �µm Laser Pulse from a Periodically Poled �mol% MgO-Doped LiNbO� Optical Parametric OscillatorRaviBhushan*,HidetsuguYoshida,KojiTsubakimoto,HisanoriFujita,MasahiroNakatsuka,NoriakiMiyanaga,YasukazuIzawa,HidekiIshizuki1,andTakunoriTaira1
(ReceivedDecember17,2007;acceptedJanuary21,2008;publishedonlineFebruary8,2008)
Wereportonanopticalparametricoscillator(OPO)basedonalarge
apertureperiodicallypoled5mol%MgO-dopedLiNbO3 (PPMgLN).A
highaveragepowerQ-switchedNd:YAGlaseroperatingat1.064µm
producing10nspulsesatarepetitionrateof10Hzwasusedtopump
theOPO. Total outputpulse energyof126mJat2µmwith62 %
slopeefficiencywasachievedatrelatively lowpumppower intensity.
Temperaturetuningbehaviorofthequasi-phasematchedOPOwasalso
observed.[DOI:10.1143/APEX.1.022007]
InstituteofLaserEngineering,OsakaUniversity,2-6Yamada-oka,Suita,Osaka565-0871,Japan1 LaserResearchCenterforMolecularScience,InstituteforMolecularScience,38
Nishigonaka,Myodaiji,Okazaki,Aichi444-8585,Japan* E-mailaddress:bhushan@ile.osaka-u.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 022008
Cylindrical Vector Laser Beam Generated by the Use of a Photonic Crystal MirrorYuichiKozawa,ShunichiSato,TakashiSato1,YoshihikoInoue1,YasuoOhtera2,andShojiroKawakami1,3
(ReceivedDecember12,2007;acceptedJanuary21,2008;publishedonlineFebruary15,2008)
Aconcentricallypatternedphotoniccrystalmirrorwithpolariza-
tionselectivity fabricatedby theautocloningtechniquewasusedfor
thegenerationofradiallyandazimuthallypolarizedbeamsfromanNd:
YAGlasercavity.Byadoptingthephotoniccrystalmirrorastheoutput
couplerofthecavity,bothradiallyandazimuthallypolarizedbeamswere
obtainedwithsimilaroutputpoweras thatofanunpolarizedbeam
generatedbyaconventional,non-polarization-selectiveoutputcoupler.
[DOI:10.1143/APEX.1.022008]
InstituteofMultidisciplinaryResearchforAdvancedMaterials,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai980-8577,Japan1 PhotonicLattice,Inc.,AobaIncubationSquare,AramakiazaAoba,Aoba-ku,Sendai
980-0845,Japan2 BiomedicalEngineeringResearchOrganization,TohokuUniversity,6-6-11Aramakiaza
Aoba,Aoba-ku,Sendai980-8579,Japan3 SendaiFoundationofAppliedInformationTechnology,AobaIncubationSquare,Aramaki
azaAoba,Aoba-ku,Sendai980-0845,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 022009
Octave Spanning High Quality Super Continuum Generation Using �0nJ and �0�fs High Energy Ultrashort Soliton PulseNorihikoNishizawa*andMasaruHori1(ReceivedDecember21,2007;acceptedJanuary24,2008;publishedonlineFebruary15,2008)
Octavespanninghighqualitysupercontinuumisgenerated inall
fibresystem.A10nJand104fshighenergyultrashortsolitonpulse is
generatedfrom1psfiberchirpedpulseamplification laserusing large
modeareaphotoniccrystal fibre.Theconversionefficiency from1ps
pulse intoultrashortsolitonpulse is33%.A1.05–2.20µmoverone
octavespanninghighqualitysupercontinuumwith±5dBuniformity is
generatedusingthehighenergysolitonpulseandhighlynonlinearfiber.
[DOI:10.1143/APEX.1.022009]
DivisionofAdvancedScienceandBiotechnology,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan1 DepartmentofElectronicalEngineeringandComputerScience,GraduateSchoolof
Engineering,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan* E-mailaddress:nishizawa@mls.eng.osaka-u.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 023001
Nearly Temperature-Independent Saturation Drain Current in a Multi-Mesa-Channel AlGaN/GaN High Electron Mobility TransistorTakahiroTamura*,JunjiKotani,SeiyaKasai,andTamotsuHashizume**
(ReceivedDecember8,2007;acceptedJanuary21,2008;publishedonlineFebruary15,2008)
Wefabricatedamulti-mesa-channel (MMC)structureby forming
aperiodictrench justunderagateelectrodetoimprovetheuniformity
ofeffectiveelectricfieldinthechannel inanAlGaN/GaNhighelectron
mobilitytransistor(HEMT).Auniqueperformance,i.e.,anearlytemper-
ature-independentsaturationdraincurrent,wasobservedintheMMC
device inawide temperature range.A two-dimensional (2D)poten-
tialcalculation indicatesthatthemesa-sidegateeffectivelymodulates
thepotential, resulting inafieldsurrounding2Delectrongas.Sucha
surrounding-fieldeffectandarelatively lowersourceaccessresistance
mayberelatedtoauniquecurrentbehaviorintheMMCHEMT.
[DOI:10.1143/APEX.1.023001]
ResearchCenterforIntegratedQuantumElectronicsandGraduateSchoolofInformationScienceandTechnology,HokkaidoUniversity,N13,W8,Kita-ku,Sapporo060-8628,Japan* E-mailaddress:tamura@rciqe.hokudai.ac.jp**E-mailaddress:hashi@rciqe.hokudai.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.2 (2008) 024001
Coulomb Blockade Oscillations in Narrow Corrugated Graphite RibbonsHisaoMiyazaki1,2,ShunsukeOdaka1,3,TakashiSato4,ShoTanaka4,HidenoriGoto2,4,AkinobuKanda2,4,KazuhitoTsukagoshi1,2,5,*,YouitiOotuka4,andYoshinobuAoyagi1,2,3
(ReceivedNovember8,2007;acceptedDecember22,2007;publishedonlineJanuary25,2008)
We reportCoulombblockadeoscillations inanatomically thin
graphiteribbonfabricatedbythemicromechanicalcleavagetechnique.
Aperiodiccurrentoscillationsasa functionof thegatevoltage indi-
catetheformationofmultipleCoulombislandsinsidethethingraphite
ribbon.WeconcludethattheCoulombislandsoriginatefrompuddles
ofelectronsandholescausedbytheinhomogeneousinterfacebetween
theribbonandthesubstrate.[DOI:10.1143/APEX.1.024001]
1 RIKEN,Wako,Saitama351-0198,Japan2 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan3 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,
Midori-ku,Yokohama226-8502,Japan4 InstituteofPhysicsandTsukubaResearchCenterforInterdisciplinaryMaterialsScience,
UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan5 NationalInstituteofAdvancedIndustrialScienceandTechnology,Umezono,Tsukuba,
Ibaraki305-8568,Japan* E-mailaddress:tsuka@riken.jp
Appl. Phys. Express Vol.1, No.2 (2008) 024002
Performance Estimation of Graphene Field-Effect Transistors Using Semiclassical Monte Carlo SimulationNaokiHarada*,MariOhfuti,andYujiAwano(ReceivedNovember16,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)
AsemiclassicalMonteCarlo simulationwas run toestimate the
performancesofamonolayerandabilayer (withverticalelectric field
of1V/nmapplied)graphene-channel field-effect transistor (FET).The
vertical fieldproducesabandgapof0.16eVandgivessemiconduc-
tivepropertiesinthebilayergraphene.Electronsinmonolayergraphene
showanotablevelocityovershootofupto7.6×107cm/s.Asub-0.1ps
transittimeisalsoexpectedina65-nmchanneldevice.Theperformance
ofabilayergraphene-channelFET is inferiortoamonolayergraphene
one,butcomparablewiththatofanInPhighelectronmobilitytransistor
(HEMT).Thislowerperformancemaybeattributedtotheelectroneffec-
tivemassproducedbytheverticalfield.[DOI:10.1143/APEX.1.024002]
NanotechnologyResearchCenter,FujitsuLaboratoriesLtd.,Atsugi,Kanagawa243-0197,Japan* E-mailaddress:harada.naoki@jp.fujitsu.com
Appl. Phys. Express Vol.1, No.2 (2008) 024003
Electrostatic Imprint Process for GlassHidekiTakagi,Shin-ichiMiyazawa,MasaharuTakahashi,andRyutaroMaeda(ReceivedNovember27,2007;acceptedJanuary5,2008;publishedonlineFebruary1,2008)
Inusual thermal imprintprocess,moldpatternsaretransferredby
applyingmechanicalpressuresatelevatedtemperatures.Wehavedevel-
opedanewimprintprocessforglass,whichutilizeselectrostaticforceas
adrivingforcefordeformation.Inthemethod,highdcvoltageisapplied
betweenamoldandaglassspecimensothat themoldbecomesan
anode.Thismethodenablesglassformingat lowertemperatureswith
smallermechanicalforcecomparedtousualthermalimprintprocess. In
addition,thismethodissuitableforsmallpatterns lessthan1µm.It is
expectedthatthismethodrealizes large-areaandhigh-efficiencynano-
formingprocessforglass.[DOI:10.1143/APEX.1.024003]
AdvancedManufacturingResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Tsukuba,Ibaraki305-8564,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 025001
Nitrogen–Oxygen Complexes Associated with Shallow Thermal Donors in SiliconHaruhikoOno(ReceivedDecember10,2007;acceptedJanuary27,2008;publishedonlineFebruary15,2008)
A structuralmodel isdescribed for the shallow thermaldonors
(STDs),whichtypicallyconsistofsevenidenticalabsorptionpeaksthat
arecausedbyelectronictransition.IntheSTDfamily,attentionwaspaid
to the247cm-1peak thatappears tostronglydependonthecondi-
tionofboththecrystalgrowthandtheannealing.WeexaminedNO
configurationandthesixkindsofNO+Oiconfiguration.Semi-empirical
molecularorbitalcalculationsfor thesecomplexessuggestedthatnot
onlythecomplexwiththeC2vsymmetrybutalsotheasymmetricNO+Oi
complexescouldsimultaneouslyexistintheSicrystal.Weconcludedthat
the247cm-1peak,whichwashighlyunstableandbehavedoddlyduring
annealing,mightbetheNOcomplexandthattheothersixSTDpeaks
mightcorrespondtothesixkindsofNO+Oicomplexes.
[DOI:10.1143/APEX.1.025001]
KanagawaIndustrialTechnologyCenter,Ebina,Kanagawa243-0435,Japan
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.2 (2008) 027001
Point Spread Function for the Calculation of Acid Distribution in Chemically Amplified Resists for Extreme Ultraviolet LithographyTakahiroKozawa1,2,*,AkinoriSaeki1,2,andSeiichiTagawa1,2,**
(ReceivedNovember15,2007;acceptedDecember15,2007;publishedonlineJanuary25,2008)
Theprocess simulator isakey technology inextremeultraviolet
(EUV)lithography,whichisregardedastheultimateinprojectionlithog-
raphy. The requirement for theaccuracyofprocess simulatorshas
becomeincreasinglystrictwiththeshrinkageoffeaturesize. Inchemi-
callyamplifiedEUVresists,acidgeneratorsdecomposethroughareac-
tionwiththermalizedelectrons(~25meV).Thissensitizationmechanism
ofEUVresists isanalogoustothat inducedbyanelectronbeam(EB).
However,theaciddistributioninEUVresistsisdifferentfromthatinEB
resistsbecauseofthemultispureffect,whichiscausedbythecharged
intermediatesnarrowlydistributedaroundtheabsorptionpointsofEUV
photons. Inthiswork,theauthorsformulateaproposedpointspread
functionfortheEUVlithographyprocessbasedonchemicallyamplified
resists.[DOI:10.1143/APEX.1.027001]
1 TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan
2 CREST,JapanScienceandTechnologyAgency,c/oOsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan
* E-mailaddress:kozawa@sanken.osaka-u.ac.jp**E-mailaddress:tagawa@sanken.osaka-u.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 027002
Hyper Rheology Measurement by Emission and Collision of Micro-Fluid ParticlesHideakiKutsunaandKeijiSakai(ReceivedDecember11,2007;acceptedJanuary11,2008;publishedonlineFebruary8,2008)
We introduceasystemtomeasure themechanicalpropertiesof
fluidsunderhighsheardeformationratesofupto106s -1.Thenewly
developedmicro-fluidemissionnozzleremarkablyextendedthevariety
ofliquidsto,forexample,organicsolvents,strongalkalisandacids,and
viscousfluids.Thedynamicbehaviorofafluidafterthehead-oncollision
ofthetwoemittedparticleswasobservedbythestroboscopicmethod.
Thesurfacetensionandviscosityweredeterminedfromtheresonant
frequencyanddecayconstantoftheresonantoscillationbycomparison
withnumericalsimulation.Anapproximatetheorytodescribethelarge-
amplitudeoscillationisalsopresented.[DOI:10.1143/APEX.1.027002]
InstituteofIndustrialScience,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8505,Japan
Appl. Phys. Express Vol.1, No.2 (2008) 027003
Extremely Small Proximity Effect in �0keV Electron Beam Drawing with Thin Calixarene Resist for �0�0nm� Pitch Dot ArraysSumioHosaka1,3,*,ZulfakriMohamad2,MasumiShira2,HirotakaSano2,YouYin1,AkihiraMiyachi3,andHayatoSone1
(ReceivedDecember6,2007;acceptedJanuary21,2008;publishedonlineFebruary15,2008)
Westudiedproximityeffect in30keVelectronbeam(EB)drawing
withcalixareneresistforpatternedmediaandquantumdevices.Using
about15-nm-thickcalixareneresistonSisubstrate inconventionalEB
drawingsystem,theproximityeffecthasbeenstudiedbyformingand
observing20-,25-,30-,and40-nm-pitchresistdotarraysandmeasuring
exposuredosage intensitydistribution (EID) function.Asaresult, the
proximityeffect isnegligiblesmalldue tocomparingwithsomedot
sizesincenter,sideandcornerof2µmsquarewith25×25nm2pitchdot
arrays. Inaddition,theproximityeffectparameterη inEIDfunction is
lessthan0.3.ItisclearthattheEBdrawingandcalixareneresistsystem
isverysuitable for formingultrahighpackeddotarrayspattern.We
demonstrated20×20nm2pitchresistdotarrays(about1.6Tb / in.2)with
adotdiameterofabout14nmandthesamesizeaseverywhereinthe
pattern.[DOI:10.1143/APEX.1.027003]
1 DepartmentofProductionScienceTechnology,GraduateSchoolofEngineering,GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan
2 DepartmentofNanoMaterialSystems,GraduateSchoolofEngineering,GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan
3 AdvancedTechnologyResearchCenter(ATEC),GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan
* E-mailaddress:hosaka@el.gunma-u.ac.jp
Appl. Phys. Express Vol.1, No.2 (2008) 027004
Dependence of Acid Generation Efficiency on Molecular Structures of Acid Generators upon Exposure to Extreme Ultraviolet RadiationRyoHirose,TakahiroKozawa*,SeiichiTagawa**,ToshiyukiKai1,andTsutomuShimokawa1
(ReceivedJanuary15,2008;acceptedJanuary24,2008;publishedonlineFebruary15,2008)
Thetrade-offbetweenresolution,sensitivity,andlineedgerough-
ness(LER)isthemostseriousproblemforthedevelopmentofsub-30nm
resistsbasedonchemicalamplification.Becauseof this trade-off, the
increase inacidgenerationefficiency isessentially required forhigh-
resolutionpatterningwithhighsensitivityand lowLER. In thisstudy,
weinvestigatedthedependencesofacidgenerationefficiencyonthe
molecularstructureandconcentrationofacidgeneratorsuponexpo-
suretoextremeultraviolet(EUV)radiation.Theacidgenerationefficiency
(thenumberofacidmoleculesgeneratedbyasingleEUVphoton)was
obtainedwithintheacidgeneratorconcentrationrangeof0–30wt%
forfivetypesofionicandnonionicacidgenerators.
[DOI:10.1143/APEX.1.027004]
TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 JSRCorp.,100Kawajiri-cho,Yokkaichi,Mie510-8552,Japan* E-mailaddress:kozawa@sanken.osaka-u.ac.jp**E-mailaddress:tagawa@sanken.osaka-u.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.2 (2008) 028001
Longitudinal and Transverse Coupling of the Beam Temperature Caused by the Laser Cooling of ��Mg+
MikioTanabe*,TakehiroIshikawa,MasaoNakao,HikaruSouda,MasahiroIkegami1,ToshiyukiShirai1,HiromuTongu1,andAkiraNoda1
(ReceivedNovember27,2007;acceptedDecember18,2007;publishedonlineFebruary1,2008)
Alaser-coolingexperimentofa40keV24Mg+beamwascarriedout
inthesmall laser-equippedstoragering(S-LSR).Alaserco-propagating
withthebeamandaninductionacceleratorwereutilizedintheexperi-
ment.The lowest longitudinal temperatureachieved in thepresent
experimentwas3.6Kfor3×104 ionsstored inthering. Itwasfound
thatthenumberofstoredionsisrelatedtothetemperatureatthefinal
equilibriumstateofthelasercooling.Thisrelationshowsthatthelongi-
tudinaltemperatureofthelaser-cooledbeamlinearlycoupleswiththe
transverseonethroughintra-beamscattering.
[DOI:10.1143/APEX.1.028001]
DepartmentofPhysics,GraduateSchoolofScience,KyotoUniversity,Kyoto606-8502,Japan1 AdvancedResearchCenterforBeamScience,InstituteforChemicalResearch,Kyoto
University,Gokasho,Uji,Kyoto611-0011,Japan* E-mailaddress:tanabe@kyticr.kuicr.kyoto-u.ac.jp
Appl. Phys. Express Vol.1, No.3 (2008) 031201
Synthesis and Thermoelectric Properties of Silicon Clathrates Sr�AlxGa��-xSi�0 with the Type-I and Type-VIII StructuresKengoKishimoto*,NaoyaIkeda,KojiAkai1,andTsuyoshiKoyanagi(ReceivedJanuary14,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Nominal composition Sr8AlxGa16-xSi30 (0≤x≤16) samples were
preparedbypowdermetallurgy.Thesampleswithx=0–7exhibitedthe
type-Iclathratestructure (Pm3–n,No.223),while thesampleswithx=
8–13almostexhibitedthetype-VIIIclathratestructure(I4–3m,No.217).
ThesesamplespossessedtheelectricalconductivitiesandSeebeckcoef-
ficients typicalofn-typedegeneratedsemiconductors.Theresultson
theirthermoelectricpropertiesindicatethatthetype-VIIISrAlGaSiclath-
ratewouldbeamoreefficientthermoelectricmaterial thanthetype-I
SrAlGaSi clathrate. Forexample, the type-VIII Sr8Al9Ga7Si30 sample
hadamaximumpowerfactorof11µWcm-1K-2at1000Kandaroom
temperatureHallmobilityof24cm2V-1 s-1,while thoseof the type-I
Sr8Al6Ga10Si30samplewere7µWcm-1K-2and5cm2V-1s-1,respectively.
[DOI:10.1143/APEX.1.031201]
GraduateSchoolofScienceandEngineering,YamaguchiUniversity,Ube,Yamaguchi755-8611,Japan1 MediaandInformationTechnologyCenter,YamaguchiUniversity,Ube,Yamaguchi
755-8611,Japan* E-mailaddress:kkishi@yamaguchi-u.ac.jp
Appl. Phys. Express Vol.1, No.3 (2008) 031301
Ferroelectric Polarization Reversal by a Magnetic Field in Multiferroic Y-type Hexaferrite Ba�Mg�Fe��O��KoujiTaniguchi,NobuyukiAbe1,ShintaroOhtani1,HiroshiUmetsu1,andTaka-hisaArima(ReceivedJanuary20,2008;acceptedFebruary6,2008;publishedonlineFebruary29,2008)
Coexistenceof the ferroelectricpolarizationand spontaneous
magnetizationhasbeen found inY-typehexaferriteBa2Mg2Fe12O22.
Thereversalofmagnetizationbyasmallmagneticfieldbelow~0.02T
accompaniesanelectricpolarizationreversal throughtheclampingof
ferrimagneticandferroelectricdomainwalls.Thisbehaviorcanbepoten-
tiallyusedasamagneticallyrewritableferroelectricmemoryandanelec-
tricallyrewritablemagneticmemory.[DOI:10.1143/APEX.1.031301]
InstituteofMultidisciplinaryResearchforAdvancedMaterials,TohokuUniversity,Sendai980-8577,Japan1 DepartmentofPhysics,GraduateSchoolofScience,TohokuUniversity,Sendai980-8577,
Japan
Appl. Phys. Express Vol.1, No.3 (2008) 031302
Determination of Penetration Depth of Transverse Spin Current in Ferromagnetic Metals by Spin PumpingTomohiroTaniguchi1,2,SatoshiYakata3,HiroshiImamura2,andYasuoAndo3
(ReceivedFebruary7,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Spinpumping innonmagnetic / ferromagneticmetalmultilayers is
studiedboth theoreticallyandexperimentally.Weshowthat the line
widthsoftheferromagneticresonance(FMR)spectrumdependonthe
thicknessoftheferromagneticmetallayers,whichmustnotbeinreso-
nancewiththeoscillatingmagneticfield.Wealsoshowthatthepene-
trationdepthsofthetransversespincurrentinferromagneticmetalscan
bedeterminedbyanalyzingthe linewidthsof theirFMRspectra.The
obtainedpenetrationdepths inNiFe,CoFe,andCoFeBwere3.7,2.5,
and12.0nm,respectively.[DOI:10.1143/APEX.1.031302]
1 InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan2 NanotechnologyResearchInstitute(NRI),NationalInstituteofAdvancedIndustrialScience
andTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan3 DepartmentofAppliedPhysics,GraduateSchoolofEngineering,TohokuUniversity,Sendai
980-8579,Japan
�0JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.3 (2008) 031501
Microcrystalline Si�-xGex Solar Cells Exhibiting Enhanced Infrared Response with Reduced Absorber ThicknessTakuyaMatsui1,*,Chia-WenChang1,TomoyukiTakada1,2,MasaoIsomura2,HiroyukiFujiwara1,andMichioKondo1
(ReceivedJanuary25,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)
Thin filmp – i –n junctionsolarcells incorporatinghydrogenated
microcrystallineSi1-xGex(µc-Si1-xGex:H)absorberilayers(1µm)havebeen
fabricatedbyplasma-enhancedchemicalvapordepositioninthecompo-
sitionrangeof0≤x≤0.35.ByincreasingGecontentfromx=0to0.15–0.2,
short-circuitcurrentdensityincreasesby~5mA/cm2withspectralsensi-
tivitiesextending into the infraredwavelengths (>600nm).However,
solarcellparametersfor largerGecontents(x>0.2)areloweredbythe
increasedchargecarrierrecombinationintheµc-Si1-xGex:H i layer.Asa
result,a6.3%efficientsolarcellisobtainedatx=0.2,exhibitinginfrared
responseevenhigherthanthatofdouble-thicknessµc-Si:Hsolarcells.
Thesolarcell showsexcellentperformancestabilityunderprolonged
lightsoaking.[DOI:10.1143/APEX.1.031501]
1 ResearchCenterforPhotovoltaics,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan
2 DepartmentofElectricalandElectronicEngineering,TokaiUniversity,1117Kitakaname,Hiratsuka,Kanagawa259-1292,Japan
* E-mailaddress:t-matsui@aist.go.jp
Appl. Phys. Express Vol.1, No.3 (2008) 031701
Rare-Earth-Dependent Magnetic Anisotropy in REBa�Cu�OyAtsushiIshihara,ShigeruHorii*,TetsuoUchikoshi1,TohruS.Suzuki1,YoshioSakka2,HirakuOgino,Jun-ichiShimoyama,andKohjiKishio(ReceivedJanuary24,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)
Wereportmagneticanisotropies(Δχ)dependingonrareearth(RE)
element intheparamagneticREBa2Cu3Oy (RE123)systemasanimpor-
tantfindingofmagneto-scientificgrain-orientation.Thec-axis-oriented
RE123powdersamplesusingstaticor rotatingmagnetic fieldswere
fabricatedatroomtemperaturetoclarifyΔχ.Theireasyaxesofmagneti-
zationweremainlydominatedbysecond-orderStevensfactors,whereas
|Δχ| largelydependedonyandREelements.Especially forheavyRE
elements, |Δχ| reachedtheorderof10-4, indicating thatappropriate
choiceofREdirectly leadstoadrasticreductionofrequiredmagnetic
fieldsforgrain-orientationofRE123.[DOI:10.1143/APEX.1.031701]
DepartmentofAppliedChemistry,UniversityofTokyo,Tokyo113-8656,Japan1 NanoCeramicsCenter,NationalInstituteforMaterialsandScience,Tsukuba,Ibaraki
305-0047,Japan2 WPICenterforMaterialsNanoarchitectonics,NationalInstituteforMaterialsandScience,
Tsukuba,Ibaraki305-0047,Japan* E-mailaddress:tholy@mail.ecc.u-tokyo.ac.jp
Appl. Phys. Express Vol.1, No.3 (2008) 031702
Time Resolution Improvement of Superconducting NbN Stripline Detectors for Time-of-Flight Mass SpectrometryKojiSuzuki*,ShigehitoMiki1,ShigetomoShiki,ZhenWang1,andMasatakaOhkubo(ReceivedJanuary25,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)
Wehaveappliedsuperconductingstriplinedetectors (SSLDs) for
time-of-flightmassspectrometry (TOF-MS)asmoleculedetectors.Two
SSLDs,whichconsistof7-nm-thickniobiumnitride(NbN)striplineswith
differentlinewidthsof200or300nmonaMgOsubstrate,werefabri-
catedto investigate theeffectsofkinetic inductanceontimeresolu-
tion.Wehaveobservedultrafast iondetectionsignalswithrisetimes
of360–640ps,andsuccessfullyobtainedmassspectraforapeptide,
AngiotensinI,andaprotein,bovineserumalbumin(BSA)atanenergy
of17.5keV.Ithasbeenconfirmedthattheresponsetimeisgovernedby
thekineticinductanceofthenano-striplines.
[DOI:10.1143/APEX.1.031702]
ResearchInstituteofInstrumentationFrontier,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan1 NationalInstituteofInformationandCommunicationsTechnology,Kobe651-2492,Japan* E-mailaddress:suzuki-ssm@aist.go.jp
Appl. Phys. Express Vol.1, No.3 (2008) 031703
Effect of c-Axis-Correlated Disorders on the Vortex Diagram of the Pinning StateMasafumiNamba,SatoshiAwaji,KazuoWatanabe,TsutomuNojima1,SatoruOkayasu2,MasashiMiura3,YusukeIchino3,YutakaYoshida3,YoshiakiTakai3,TomoyaHoride4,PaoloMele4,5,andKanameMatsumoto5
(ReceivedJanuary24,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Theintroductionofthec-axis-correlateddisorderisapromisingtech-
niqueforthe improvementofthecriticalcurrentdensityJc forB//cof
REBa2Cu3Oy (RE123)filmsandtapes. Inordertounderstandthevortex
pinningmechanismwith thedifferentvarietyof thec-axis-correlated
disorder, theangulardependenceofJcwasmeasured indetail foran
Y123filmwithBaZrO3nano-rods,aSm123filmwithfinenano-particles
andedgedislocationsandanY123filmwithcolumnardefects intro-
ducedbytheheavy-ionirradiationparalleltothec-axis.Wefoundthat
thevortexpinningstateforthevarietyofthec-axis-correlatedpinning
issimilar in lowfieldsbelowthematchingfield,but itshowsdifferent
behaviorsinhighfieldsabovethematchingfield.Itisconsideredthatthe
interstitialvorticesinteractedwiththec-axis-correlateddisordersthrough
thevortexinteractionmayplayanimportantrolefortheappearanceof
thec-axis-correlatedpinningbehavior inahigh-fieldregionabovethe
matchingfield.[DOI:10.1143/APEX.1.031703]
HighFieldLaboratoryforSuperconductingMaterials,InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan1 InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan2 JapanAtomicEnergyAgency,Tokai-mura,Naka-gun,Ibaraki319-1195,Japan3 NagoyaUniversity,Nagoya464-8603,Japan4 KyotoUniversity,Kyoto606-8501,Japan5 KyushuInstituteofTechnology,Kitakyushu804-8550,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.3 (2008) 032001
Reduction of Viewing-Angle Dependent Color Shift in a Reflective Type Cholesteric Liquid Crystal Color FilterWon-GunJang*,TaeWonBeom1,HaoCui1,JongRakPark1,SeongJinHwang2,YoungJinLim2,andSeungHeeLee2
(ReceivedJanuary3,2008;acceptedJanuary24,2008;publishedonlineFebruary22,2008)
Thereflectivetypecolorfilter for the liquidcrystaldisplays (LCDs)
wasproducedusingcholesteric liquidcrystalmonomerswhosephase
ischaracterizedbytheuniqueoptical featuresofselective reflection.
Periodicmicrometerscalehemi-sphericalphotoresist (PR)patternswere
formedonglasssubstratesbythermalreflowmethodafterphotolithog-
raphy.Cholestericcolorfilterfilmsforred,green,andbluelightreflec-
tionswerethenproducedandtheviewingangledependencewasinves-
tigatedandcomparedwiththatofreflectedlightonthenon-patterned
substrates.Computersimulationsusing“LightTools”werealsocarried
out,and itwasconfirmedthatthecolorshiftsweremuchsmalleron
thepatternedsubstratesbybareeyesandCommission Internationale
de'Eclairage(CIE)chromaticitycoordinationanalysisqualitatively.
[DOI:10.1143/APEX.1.032001]
KoreaPhotonicsTechnologyInstitute,Wolchul-dong,Buk-gu,Gwangju500-460,Korea1 DepartmentofPhotonicEngineering,ChosunUniversity,375Seosok-dong,Dong-gu,
Gwangju501-759,Korea2 BK-21PolymerBINFusionResearchTeam,ResearchCenterofIndustrialTechnology,School
ofAdvancedMaterialsEngineering,ChonbukNationalUniversity,Chonju,Chonbuk561-756,Korea
* E-mailaddress:wgjang@kopti.re.kr
Appl. Phys. Express Vol.1, No.3 (2008) 032002
Lowering Threshold by Energy Transfer between Two Dyes in Cholesteric Liquid Crystal Distributed Feedback LasersKojiSonoyama,YoichiTakanishi*,KenIshikawa,andHideoTakezoe(ReceivedDecember7,2007;acceptedFebruary8,2008;publishedonlineFebruary29,2008)
LoweringlasingthresholdbasedontheFörster-typeenergytransfer
processhasbeenstudiedindistributedfeedback(DFB)lasersofcholes-
tericliquidcrystals(CLCs)containingtwodyes.Wefoundthatthelasing
thresholdintheenergytransferprocesswasloweredtolessthanhalfof
thatindirectexcitationprocesses.Thiseffectisattributedtothesuppres-
sionofself-absorptionofadye(acceptor).Thisprovidesamethodfor
loweringthreshold inCLC-DFBlaserscontainingmultipledyesparticu-
larlywithasmallStokesshift.[DOI:10.1143/APEX.1.032002]
DepartmentofOrganicandPolymericMaterials,TokyoInstituteofTechnology,2-12-1-S8-42O-okayama,Meguro-ku,Tokyo152-8552,Japan* Presentaddress:DepartmentofPhysics,KyotoUniversity,Kitashirakawa-oiwake-cho,Sakyo-
ku,Kyoto606-8502,Japan.
Appl. Phys. Express Vol.1, No.3 (2008) 032003
Second Harmonic Generation with High Conversion Efficiency and Wide Temperature Tolerance by Multi-Pass SchemeTetsuroMizushima*,HiroyukiFuruya,ShinichiShikii,KoichiKusukame,KiminoriMizuuchi,andKazuhisaYamamoto(ReceivedJanuary21,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)
Weproposedamulti-passsecondharmonicgenerationschemein
whichcondensedfundamental lightpassedthroughanonlinearcrystal
manytimes.Themulti-passschemewasrealizedbyusingawideperi-
odically-poledMgO:LiNbO3,concavemirrorsandcondensingoptics.The
totalwavelengthconversionefficiencyof themulti-passschemewas
increasedbecausenon-convertedfundamental lightwhichhadpassed
throughthenonlinearcrystalwasre-injectedandcondensed intothe
nonlinearcrystalandconverted.Moreoverthetotal temperaturetoler-
anceofthemultipasseswaswidenedbecausethefundamentalbeam
passeshaddifferentphase-matchingtemperatureandcompensatedfor
missconversionsofotherpasses. In thiswork,continuous-wave5W
greenlight(532nm)with66%conversionefficiencyandwidetempera-
turetolerancewereobtained.[DOI:10.1143/APEX.1.032003]
AVCoreTechnologyDevelopmentCenter,MatsushitaElectricIndustrialCo.,Ltd.,3-1-1Yagumo-naka-machi,Moriguchi,Osaka570-8501,Japan* E-mailaddress:mizushima.tetsuro@jp.panasonic.com
Appl. Phys. Express Vol.1, No.3 (2008) 032004
Green Photoluminescence from GaInN Photonic CrystalsHitoshiKitagawa1,2,*,ToshihideSuto1,2,MasayukiFujita1,**,YoshinoriTanaka1,TakashiAsano1,andSusumuNoda1,3,***
(ReceivedDecember21,2007;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Wehave investigatedgreen-emittingGaInN two-dimensional
photoniccrystalswithairholesthatpenetratethroughtheactivelayer.
Atroomtemperature,theobservedphotoluminescence intensityfrom
thephotoniccrystal isapproximatelythreetimesthatofasamplewith
nophotoniccrystalstructure.Thisisduetothelowsurfacerecombina-
tionvelocity(1.4×103cm/s)ofGaInNattheairholeedgesandahigher
degreeoflightextractionbythediffractioneffect.
[DOI:10.1143/APEX.1.032004]
1 DepartmentofElectronicScienceandEngineering,KyotoUniversity,Kyotodaigaku-katsura,Nishikyo-ku,Kyoto615-8510,Japan
2 ProcessTechnologyDVLPMT.CenterALPSElectricCo.,Ltd.,Sendai981-3208,Japan3 PhotonicsandElectronicsScienceandEngineeringCenter,KyotoUniversity,Kyotodaigaku-
katsura,Nishikyo-ku,Kyoto615-8510,Japan* E-mailaddress:kitagawa@qoe.kuee.kyoto-u.ac.jp**E-mailaddress:fujita@qoe.kuee.kyoto-u.ac.jp***E-mailaddress:snoda@kuee.kyoto-u.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.3 (2008) 034001
Position-Controlled Si Nanocrystals in a SiO� Thin Film Using a Novel Amorphous Si Ultra-Thin-Film “Nanomask” due to a Bio-Nanoprocess for Low-Energy Ion ImplantationYujiNakama*,ShinjiNagamachi1,JunOhta,andMasahiroNunoshita(ReceivedJanuary22,2008;acceptedFebruary4,2008;publishedonlineFebruary22,2008)
Anano-sizeandpositioncontrollingtechniqueofsilicon-nanocrystal
(Si-NC)assemblies inaSiO2 thin filmhasbeen investigatedbyusing
low-energyionimplantation(0.6keV)throughanovelamorphoussilicon
(a-Si)ultra-thin-film“nanomask”.Thisa-Sinanomaskwasdevelopedon
thebasisofaself-assembledbio-nanoprocesswithproteins“ferritin”.Si
NCsweresynthesizedfromtheexcessSi+ionsimplantedinaSiO2matrix
byannealingwithaNd:YAGpulsed laser.Asaresult,almostordered
Si-NCassemblieswithverysmallanduniformsize(3.0±0.3nm)andinter-
particleseparation(5to6nm)wereobtainedbythetranscriptionofthe
a-Sinanomaskpattern.[DOI:10.1143/APEX.1.034001]
GraduateSchoolofMaterialsScience,NaraInstituteofScienceandTechnology,8916-5Takayama,Ikoma,Nara630-0101,Japan1 IonEngineeringResearchInstituteCorporation,2-8-1Tudayamate,Hirakata,Osaka
573-0128,Japan* E-mailaddress:n-yuuji@ms.naist.jp
Appl. Phys. Express Vol.1, No.3 (2008) 034002
Carbon Nanotubes from a Divided Catalyst: the Carbon Transmission MethodTakeshiHikata,KazuhikoHayashi,TomoyukiMizukoshi1,YoshiakiSakurai1,ItsuoIshigami1,TakaakiAoki2,ToshioSeki2,andJiroMatsuo2
(ReceivedJanuary23,2008;acceptedFebruary4,2008;publishedonlineFebruary22,2008)
Wehave fabricatedcarbonnanotubes (CNTs)usingacatalyzed
growthtechniquethatwecall thecarbontransmissionmethod(CTM).
Wecouldcontrolindependentlyfunctionsforcarbonsourcegassupply
andCNTgrowthbyusingafoilbarrier(Ag)penetratedbypureFefibers.
CNTsgrewononeendoftheFefibers, formedfromdiffusedcarbon
thatoriginatesincarbonsourcegasattheotherendofthefibers.Long
CNTswithlengthover100µmwereobtainedontheendoftheFefibers
inthecarbontransmittedside.[DOI:10.1143/APEX.1.034002]
SumitomoElectricIndustries,Ltd.,Osaka554-0024,Japan1 TechnologyResearchInstituteofOsakaPrefecture,Osaka594-1157,Japan2 FacultyofEngineeringQuantumScienceandEngineeringCenter,KyotoUniversity,Kyoto
606-8501,Japan
Appl. Phys. Express Vol.1, No.3 (2008) 034003
Optical and Conductive Characteristics of Metallic Single-Wall Carbon Nanotubes with Three Basic Colors; Cyan, Magenta, and YellowKazuhiroYanagi*,YasumitsuMiyata,andHiromichiKataura(ReceivedFebruary1,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)
Wepresentprotocols topreparehigh-puritymetallic single-wall
carbonnanotubes(SWCNTs)withthreebasiccolors,cyan,magenta,and
yellow,throughdensitygradientcentrifugations.Additionofdeoxycho-
latesodiumsaltsasaco-surfactantcouldimproveseparationcapability
formetallicSWCNTsincentrifugations.Weappliedtheimprovedsepara-
tionprotocolstotheSWCNTswithdifferentaveragediameters(1.34,1.0,
and0.84nm),andobtainedthemetallicSWCNTswithcyan,magenta,
andyellowcolors.Theiroptical / conductivecharacteristicswererevealed,
andconductivecolorfilmswereformedfromthemetallicSWCNTs.
[DOI:10.1143/APEX.1.034003]
JST/CREST,NanotechnologyResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnologies(AIST),Tsukuba,Ibaraki305-8562,Japan* E-mailaddress:k-yanagi@aist.go.jp
Appl. Phys. Express Vol.1, No.3 (2008) 034004
High-Quality Carbon Nanotube Growth at Low Temperature by Pulse-Excited Remote Plasma Chemical Vapor DepositionYuichiYamazaki,NaoshiSakuma,MasayukiKatagiri,MarikoSuzuki,TadashiSakai,ShintaroSato1,MizuhisaNihei1,andYujiAwano1
(ReceivedJanuary24,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)
Carbonnanotube(CNT)growthattemperaturesbelow400°Cby
pulse-excitedremoteplasmachemicalvapordepositionwasdemon-
strated.Reductionofplasmapowerwascarriedoutinordertodecrease
theamountofallparticles, ions,electrons,andradicals. Inaddition,
abiasedplate-typescreeningelectrodewas introducedtoremovalof
chargedparticles, ions,andelectrons.Thenegativebiasbelow50V
wasmosteffectiveforgrowthrate.High-qualityCNTgrowthwiththe
growth rateof98nm/minwas successfullyobtainedat400°C.The
resultssuggestthatbothremovalofchargedparticlesandcontrolofthe
amountofradicalsareimportantforhigh-qualityCNTgrowthattemper-
aturesbelow400°C.[DOI:10.1143/APEX.1.034004]
MIRAI–Selete,1Komukai-Toshiba-cho,Saiwai-ku,Kawasaki212-8582,Japan1 MIRAI–Selete,10-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0197,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.3 (2008) 034005
Real-Time Observation of Growth of Tungsten Oxide Nanowires with a Scanning Electron MicroscopeKeigoKasuya*,TakeshiOoi**,YusukeKojima,andMasayukiNakao(ReceivedJanuary30,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)
Weobservedthegrowthprocessof tungstenoxidenanowires in
real-timewithafieldemissionscanningelectronmicroscope(SEM).The
observationwasperformedbyanewin-situobservationsystemdesigned
toperformtwofunctions:heatingoftungstenfilmandlocalsupplyof
O2gas.Thenanowiresgrewafterthenucleationonthesurface.Their
lengthextendedwithtimekeepingthedirectionconstant.Thegrowth
ratedecreasedwithexponential.[DOI:10.1143/APEX.1.034005]
DepartmentofEngineeringSynthesis,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan* Presentaddress:CentralResearchLaboratory,HitachiLtd.,1-280Higashi-koigakubo,
Kokubunji,Tokyo185-8601,Japan.E-mailaddress:keigo.kasuya.bp@hitachi.com**Presentaddress:KomatsuLtd.,1200Manda,Hiratsuka,Kanagawa254-8567,Japan
Appl. Phys. Express Vol.1, No.3 (2008) 034006
Adsorption Properties of a Gold-Binding Peptide Assessed by its Attachment to a Recombinant Apoferritin MoleculeKazutakaIshikawa1,KiyohitoYamada1,2,ShinyaKumagai2,Ken-IchiSano3,4,KiyotakaShiba3,4,IchiroYamashita1,2,4,andMimeKobayashi1,4,*
(ReceivedJanuary10,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Theadsorptionpropertiesofarecombinantapoferritinproteinfused
toagold-bindingpeptidewerecharacterized.The resultsofquartz
crystalmicrobalancemeasurementsshowedthatthefusionproteinpref-
erentiallyadsorbstogoldsurfaces.Scanningelectronmicroscopyalso
revealedthattheproteinselectivelyadsorbedontoananometer-scale
goldpatternonaSiO2surfacefabricatedbyelectron-beamlithography.
Ourresults indicatethatnanodotsandnanowiressynthesizedusinga
biotemplatecanbeselectivelyplacedontoagoldsurfacebygenetically
modifyingtheoutersurfaceofthebiotemplate.This techniquerepre-
sentsan importantsteptowardbiotemplate-mediatedfabricationofa
nanometer-scaleddevicethatutilizesgoldelectrodes.
[DOI:10.1143/APEX.1.034006]
1 GraduateSchoolofMaterialsScience,NaraInstituteofScienceandTechnology,Ikoma,Nara630-0192,Japan
2 AdvancedTechnologyResearchLaboratories,MatsushitaElectricIndustrialCo.,Ltd.,Hikaridai,Seika,Kyoto619-0237,Japan
3 DepartmentofProteinEngineering,CancerInstitute,JapaneseFoundationforCancerResearch,Koto-ku,Tokyo135-8550,Japan
4 CoreResearchforEvolutionalScienceandTechnology,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan
* E-mailaddress:mime@ms.naist.jp
Appl. Phys. Express Vol.1, No.3 (2008) 034007
Inter-Layer Screening Length to Electric Field in Thin Graphite FilmHisaoMiyazaki1,2,ShunsukeOdaka1,3,TakashiSato4,ShoTanaka4,HidenoriGoto2,4,AkinobuKanda2,4,KazuhitoTsukagoshi1,2,5,*,YouitiOotuka4,andYoshinobuAoyagi1,2,3
(ReceivedJanuary19,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)
Electricconductioninthingraphitefilmwastunedbytwogateelec-
trodestoclarifyhowthegateelectricfieldinduceselectriccarriersinthin
graphite.Thegraphitewassandwichedbetweentwogateelectrodes
arrangedinatopandbottomgateconfiguration.Ascanofthetopgate
voltagegeneratesaresistancepeak inambiploarresponse.Theambi-
polarpeakisshiftedbythebottomgatevoltage,wheretheshiftrate
dependsonthegraphitethickness.Thethickness-dependentpeakshift
wasclarifiedintermsoftheinter-layerscreeninglengthtotheelectric
field inthedouble-gatedgraphitefilm.Thescreeninglengthof1.2nm
wasexperimentallyobtained.[DOI:10.1143/APEX.1.034007]
1 RIKEN,Wako,Saitama351-0198,Japan2 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan3 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,
Midori-ku,Yokohama226-8502,Japan4 InstituteofPhysicsandTsukubaResearchCenterforInterdisciplinaryMaterialsScience,
UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan5 AdvancedIndustrialScienceandTechnology,Higashi,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:tsuka@riken.jp
Appl. Phys. Express Vol.1, No.3 (2008) 035001
A Heterojunction Photodiode Operating at Inorganic Nanosheet InterfacesHisakoSato,KentaroOkamoto1,KenjiTamura2,HirohisaYamada2,KazukoSaruwatari,ToshihiroKogure,andAkihikoYamagishi1,2,*
(ReceivedNovember12,2007;acceptedFebruary4,2008;publishedonlineFebruary22,2008)
Aheterojunctionphotodiodewasfabricatedbyformingtwocontact
regionsonaglasssubstrate:onesidewasacastfilmofperovskite-type
niobate[(CH3)3NHSr2Nb3O10]asan-typephotosemiconductorandthe
othersideacastfilmofZn-saponite(Na0.96[Si7.18Al0.64]Zn6.20O20(OH)2)as
ap-typesemiconductorunderoxygenatmosphere.Diode-typecurrent–
voltagecharacteristicswereobtainedunder the illuminationof light
(340nm)andoxygenatmosphere (1atm)at25 –100°C.The interfa-
cialstructurewasstudiedbymeansoffocusedion-beamandtransmis-
sionelectronmicroscopytechniques,confirmingthecontactofthetwo
differentnanosheetsonananometerscale.Theresultsarediscussedon
thebasisofthenanosheetbandstructures.
[DOI:10.1143/APEX.1.035001]
GraduateSchoolofScience,TheUniversityofTokyo,Tokyo113-0013,Japan1 FacultyofScience,OchanomizuUniversity,Tokyo112-8610,Japan2 PhotocatalyticMaterialsCenter,NationalInstituteforMaterialsScience,Tsukuba,Ibaraki
305-0044,Japan* E-mailaddress:yamagishi.akihiko@ocha.ac.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.3 (2008) 035002
Influence of Substrates on Initial Growth of Diamond-Like Carbon FilmsNobutoYasui1,2,HiroshiInaba1,andNaotoOhtake3
(ReceivedNovember24,2007;acceptedFebruary11,2008;publishedonlineFebruary29,2008)
We investigated the influenceofsubstratematerialsonbonding
structureofdiamond-likecarbon (DLC) films, fabricatedby filtered
cathodicvacuumarc,byusingX-rayphotoelectronspectroscopyand
secondary ionmassspectroscopy.Twokindsofsubstratematerials,Si
andNiFe,wereevaluated.Theresultsshowedthatsp3ratioofDLCfilms
onNiFewaslowerthanthatonSibyapproximately10%,andimplies
that thediffusionofNeandFe intoDLC films inhibits sp3bonding
formation.[DOI:10.1143/APEX.1.035002]
1 ProductionEngineeringResearchLaboratory,Hitachi,Ltd.,Yokohama244-0817,Japan2 DepartmentofMechanicalSciencesandEngineering,TokyoInstituteofTechnology,Tokyo
152-8552,Japan3 GraduateSchoolofEngineering,NagoyaUniversity,Nagoya464-8603,Japan
Appl. Phys. Express Vol.1, No.3 (2008) 035003
Near-Surface Defects in Boron-Doped Diamond Schottky Diodes Studied From Capacitance TransientsPierreMuret,JulienPernot,TokuyukiTeraji1,andToshimichiIto2
(ReceivedJanuary17,2008;acceptedJanuary31,2008;publishedonlineFebruary29,2008)
Transientcapacitancespectroscopyofdeepenergy levels (DLTS) in
thebandgapofboron-dopedhomoepitaxialdiamonddisplaystwotypes
ofdefectwhentemperatureisraisedfrom250to650K.Thefirsttrapis
astronglyattractivecenterforholeswhilethesecondoneisrepulsive,
withrespectiveactivationenergiesof1.57and1.15eV.Concentration
profileisnon-monotonicforthefirsttrapandchangeswhenthediode
undergoesrepetitivetemperaturecycles.Analysisofall thedatashows
thatthedeepcentersfoundinthisstudycomefromstructuraldefects,
eventuallyassociatedwithachargedimpurity.
[DOI:10.1143/APEX.1.035003]
InstitutNéel,CentreNationaldelaRechercheScientifiqueandUniversitéJosephFourierBP166,38042GrenobleCedex9,France1 SensorMaterialsCenter,NationalInstituteforMaterialsScience,1-1Namiki,Tsukuba,
Ibaraki305-0044,Japan2 GraduateSchoolofEngineering,OsakaUniversity,2-1Yamada-oka,Suita,Osaka565-0871,
Japan
Appl. Phys. Express Vol.1, No.3 (2008) 035004
Nitrogen Gas Flow Driven Unintentional Incorporation of Al during the Growth of Dilute Nitride Semiconductor by Plasma-Assisted Molecular Beam EpitaxyShudongWu,MasakazuKato,MasayukiUchiyama,KotaroHigashi,FumitaroIshikawa,andMasahikoKondow(ReceivedJanuary30,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)
Wereporttheunintentional incorporationofAlduringthegrowth
ofmolecularbeamepitaxyusingRFplasmasource,drivenbyN2gas
flow.TheconcentrationsofN,Al,O,andCwithinGaNAs/GaAs/AlAs
structureareinvestigatedbysecondaryionmassspectrometry.Inspiteof
theclosedshutterofAlcell,weobserveAlincorporationwithaconcen-
trationupto1×1018cm-3 inGaNAs layerandcharacteristically in the
bottomsideGaAs.ItsconcentrationissolelydependentonN2gasflow
rate.Remarkably,theoperationoftheRFplasmahasnoimpactonthat.
CandOshowtheirconcentrationscorrespondingtotheextrinsicAl.The
complexinteractionsbetweenthoseelementspredictapossibleoriginof
materialdeteriorationsanddifficultyfortheprecisedopingcontrol.
[DOI:10.1143/APEX.1.035004]
GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan
Appl. Phys. Express Vol.1, No.3 (2008) 036001
Difference in Reaction Schemes in Photolysis of Triphenylsulfonium Salts between ���nm and Dry/Wet ���nm ResistsYoshinoriMatsui*,HidekazuSugawara,ShuSeki,TakahiroKozawa,SeiichiTagawa**,andToshiroItani1(ReceivedJanuary11,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)
Chemicallyamplified (CA) resistsare important in the semicon-
ductorindustrybecauseoftheirhighordersofmagnitudeofsensitivity
enhancement.ThekeycomponentsofCAresistsareapolymerwithan
acidlabilegroupandaphotoacidgenerator(PAG)thatproducesanacid
uponexposuretoradiation.AlthoughthephotolysisofPAGshasbeen
intensivelystudied,thedifferenceinreactionschemesbetween248and
193nmresistshadnotbeenclarified.Inthiswork,wehavefocusedon
thereactionofPh2S•+,which isoneofthemajor intermediates inthe
photolysisoftriphenylsulfoniumtriflate. Itwasrevealedthatthediffer-
enceinreactionschemesbetween248and193nmresistsiscausedby
theionmolecularreactionsofapolymerradicalcationproducedbyelec-
trontransferfromthepolymertoPh2S•+.
[DOI:10.1143/APEX.1.036001]
TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 SemiconductorLeadingEdgeTechnologies,Inc.,16-1Onogawa,Tsukuba,Ibaraki305-8569,
Japan* Presentaddress:NECElectronicCorporation,1120Shimokuzawa,Sagamihara,Kanagawa
229-1198,Japan.E-mailaddress:yoshinori.matsui@necel.com**E-mailaddress:tagawa@sanken.osaka-u.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.3 (2008) 037001
Correlation Imaging of Magnetic Recorded Patterns and Grain Structures of Perpendicular Magnetic-Recording MediaYoshioTakahashi(ReceivedJanuary7,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)
Anobservation technique to imagepolycrystallineandmagnetic
structuresat the samesub-micronareaofperpendicularmagnetic-
recordingmediahasbeendeveloped.Thegranulargrainstructuresand
magneticallyrecordedbitpatternswereimagedbytransmissionelectron
microscopyandmagneticforcemicroscopy,respectively.Thesmallguide
marksfabricatedonadisksamplewithafocusedionbeamapparatus
wereusedforaligningtheimageswitheachother.Byapplyingthistech-
niquetoanalyzethemagneticallyrecordedCoCrPtSiOthinfilmlayersof
aharddiskmedium,thecorrelationbetweenthepositionsoftheclus-
teredgrainsandthepercolationofthemagneticbitpatternscouldbe
discussed.[DOI:10.1143/APEX.1.037001]
CentralResearchLaboratory,Hitachi,Ltd.,Kokubunji,Tokyo185-8601,Japan
Appl. Phys. Express Vol.1, No.3 (2008) 037002
New Technique of Manipulating a Protein Crystal Using Adhesive MaterialTomoyaKitatani1,2,ShigeruSugiyama1,2,HiroyoshiMatsumura1,2,3,HiroakiAdachi1,2,3,HiroshiY.Yoshikawa1,2,SyouMaki1,2,SatoshiMurakami2,3,4,TsuyoshiInoue1,2,3,YusukeMori1,2,3,andKazufumiTakano1,2,3,*
(ReceivedJanuary31,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)
WehavedevelopedCrystalCatcher,anewdeviceformanipulating
proteincrystals.CrystalCatcherdirectlycapturesacrystalwithanadhe-
sive.Theeasyandstableremovalofaproteincrystal fromadrophas
beenachievedusingtheCrystalCatcher.Thecrystalpickeduponthe
CrystalCatcher ispositioned in thecryostreamonagoniometerand
flash-cooled.Variousproteincrystalscanbecapturedandmounted
withoutcausingsignificantdamage.Thisnewapproachwill replace
nylonloopsforpickingupproteincrystals.
[DOI:10.1143/APEX.1.037002]
1 GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan
2 CREST,JapanScienceandTechnologyAgency,2-1Yamadaoka,Suita,Osaka565-0871,Japan
3 SOSHOInc.,1-6-18Honmachi,Chuo-ku,Osaka541-0053,Japan4 InstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,
Osaka567-0047,Japan* E-mailaddress:ktakano@mls.eng.osaka-u.ac.jp
Appl. Phys. Express Vol.1, No.3 (2008) 038001
Enhanced Transfection Efficiency in Laser-Induced Stress Wave-Assisted Gene Transfer at Low Laser Fluence by Increasing Pressure ImpulseShintaTakano,ShunichiSato1,*,MitsuhiroTerakawa,HiroshiAsida1,HideyukiOkano2,andMinoruObara(ReceivedDecember21,2007;acceptedFebruary11,2008;publishedonlineFebruary29,2008)
To improvetransfectionefficiencyingenedeliverybasedonnano-
secondpulsedlaser-inducedstresswaves,weexamineddifferenttypes
oftransparentmaterials,apoly(ethyleneterephthalate)sheet,poly(vinyl
alcohol)gel,andwater,whichwereplacedonalasertargetforplasma
confinement.Wefoundthattheuseofwaterwasmosteffectivefor
maintaininga largepressure impulseduringmultipulse laser irradiation
and,asaresult,hightransfectionefficiencywasdemonstrated inrat
skinin vivoatarelativelylowlaserfluenceof0.7J / cm2.Atthisfluence,
steadylasertransmissionthroughquartzfiberswasconfirmed,allowing
endoscopicapplicationofourgenedeliverytechnique.
[DOI:10.1143/APEX.1.038001]
DepartmentofElectronicsandElectricalEngineering,KeioUniversity,3-14-1Hiyoshi,Kohoku-ku,Yokohama223-8522,Japan1 DivisionofBiomedicalInformationSciences,NationalDefenseMedicalCollegeResearch
Institute,3-2Namiki,Tokorozawa,Saitama359-8513,Japan2 DepartmentofPhysiology,KeioUniversitySchoolofMedicine,35Shinanomachi,Shinjuku-
ku,Tokyo160-8582,Japan* E-mailaddress:shunsato@ndmc.ac.jp
Appl. Phys. Express Vol.1, No.4 (2008) 041101
Compositional Dependence of Nonpolar m-Plane InxGa�-xN/GaN Light Emitting DiodesHisashiYamada*,KenjiIso,MakotoSaito,HisashiMasui,KenjiFujito1,StevenP.DenBaars,andShujiNakamura(ReceivedFebruary12,2008;acceptedMarch3,2008;publishedonlineMarch21,2008)
Characteristicsofm-plane InGaN/GaNlightemittingdiodes (LEDs)
with various indiumcompositionswere investigated.X-raydiffrac-
tionrevealed that indiumcompositions in the InGaNmultiquantum
wells (MQWs)onm-planesubstratewere2–3timeslowerthanthose
onc-planesubstrate.Theopticalpolarizationratio form-planeLEDs
increasedfrom0.27to0.89withincreasingemissionwavelengthfrom
383to476nmduetocompressivelystrainedInGaNQWs.Theoutput
powerofelectroluminescencedecreasedabove400nmalthoughpolar-
ization-relatedinternalelectricfieldswereeliminated.
[DOI:10.1143/APEX.1.041101]
MaterialsDepartment,UniversityofCalifornia,SantaBarbara,CA93106,U.S.A.1 OptoelectronicsLaboratory,MitsubishiChemicalCo.,Ltd.,1000Higashi-Mamiana,Ushiku,
Ibaraki300-1295,Japan* E-mailaddress:yamadah7@sc.sumitomo-chem.co.jp
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.4 (2008) 041102
Hydrogen Sensing Characteristics of a Pd/AlGaN/GaN Schottky DiodeTsung-HanTsai,Huey-IngChen1,Kun-WeiLin,Ching-WenHung,Chia-HaoHsu,Tzu-PinChen,Li-YangChen,Kuei-YiChu,Chung-FuChang,andWen-ChauLiu*
(ReceivedFebruary29,2008;acceptedMarch12,2008;publishedonlineApril11,2008)
In thispaper, the interestinghydrogen sensingpropertiesofa
Pd-gateAlGaN/GaNSchottkydiodeareinvestigated.Asignificantlylow
detectionlimitof850ppbH2/airgascanbeobservedwithincreasingthe
temperatureto423K.Theexperimentalresults indicatethathydrogen
moleculescausegreatinfluencesonthediodebreakdownvoltage.Also,
thediodeexhibitsanultrahighsensingresponseof2.04×105at423K
whenexposuretoa9660ppmH2/airgas.Thetransientresponsetime
andreversibilityofthestudieddevicecanbeimprovedbyincreasingthe
operatingtemperature.[DOI:10.1143/APEX.1.041102]
InstituteofMicroelectronics,DepartmentofElectricalEngineering,NationalCheng-KungUniversity,1UniversityRoad,Tainan,Taiwan70101,R.O.C.1 DepartmentofChemicalEngineering,NationalCheng-KungUniversity,1UniversityRoad,
Tainan,Taiwan70101,R.O.C.* E-mailaddress:wcliu@mail.ncku.edu.tw
Appl. Phys. Express Vol.1, No.4 (2008) 041201
Enhanced Conversion Efficiencies of Cu�ZnSnS�-Based Thin Film Solar Cells by Using Preferential Etching TechniqueHironoriKatagiri,KazuoJimbo,SatoruYamada,TsuyoshiKamimura,WinShweMaw,TatsuoFukano1,*,TadashiIto1,andTomoyoshiMotohiro1
(ReceivedNovember12,2007;acceptedMarch7,2008;publishedonlineApril4,2008)
Cu2ZnSnS4 (CZTS) thin film solar cellshavebeen fabricatedby
co-sputteringtechniqueusingthreetargetsofCu,SnS,andZnS.CZTS-
basedthinfilmsolarcellsover6.7%efficiencywereobtainedforthe
firsttimebysoakingtheCZTSlayerontheMocoatedsoda-limeglass
substrateindeionizedwater(DIW)afterformingtheCZTSlayer. Itwas
foundthatDIW-soakinghadtheeffectofpreferentialetching,which
eliminatedselectivelymetaloxideparticlesintheCZTSlayer,byelectron
probeX-raymicroanalysis.[DOI:10.1143/APEX.1.041201]
DepartmentofElectricalandElectronicSystemsEngineering,NagaokaNationalCollegeofTechnology,888Nishikatakai,Nagaoka,Niigata940-8532,Japan1 MaterialsDepartment,ToyotaCentralResearchandDevelopmentLaboratoriesInc.,
Nagakute,Aichi480-1192,Japan* E-mailaddress:e0987@mosk.tytlabs.co.jp
Appl. Phys. Express Vol.1, No.4 (2008) 041202
Enhancement-Mode ZnO Thin-Film Transistor Grown by Metalorganic Chemical Vapor DepositionJungyolJo*,OgweonSeo1,HyoshikChoi,andByeonggonLee2
(ReceivedJanuary23,2008;acceptedMarch21,2008;publishedonlineApril11,2008)
Wedevelopedamethodtocontrol thresholdvoltageandon/off
ratioofZnOthin-filmtransistor (TFT)grownbymetalorganicchemical
vapordeposition(MOCVD).ZnOusuallyshowsoxygendeficiency,which
showsupasn-typedefectsofzincinterstitialoroxygenvacancy.Inorder
toreduce thesedefects,weallowedsufficientoxidation timeduring
growth. Insteadofone longoxidation step,we repeated thin-layer
growthandoxidation,untildesiredthickness isachieved.Byusingthis
method,wecouldobtainhighqualityZnOTFTbyMOCVD.OurZnOTFT
grownat450°Cshowed15cm2/(Vs)mobilityand107on/offratio,with
+5Vthresholdvoltage,whichenablesenhancementmodeTFTopera-
tion.[DOI:10.1143/APEX.1.041202]
DepartmentofElectricalandComputerEngineering,AjouUniversity,Suwon443-749,Korea1 NanoFabricationTechnologyCenter,SamsungAdvancedInstituteofTechnology,Suwon
440-600,Korea2 CDACo.,Ltd.,Yangjaedong,Seoul137-893,Korea* E-mailaddress:jungyol@ajou.ac.kr
Appl. Phys. Express Vol.1, No.4 (2008) 041203
Enhanced Temperature Characteristics of InGaAs/InAlGaAs Multi-Quantum-Well Lasers on Low-In-Content InGaAs Ternary SubstratesTakeshiFujisawa*,MasakazuArai,TakaakiKakitsuka,TakayukiYamanaka,YasuhiroKondo,andHiroshiYasaka(ReceivedFebruary14,2008;acceptedMarch21,2008;publishedonlineApril11,2008)
Temperaturecharacteristicsofmulti-quantum-well lasersonInGaAs
ternary substratesare investigated.Byusing InAlGaAsbarriersand
low-In-content InGaAssubstrates, thecharacteristic temperatureof
thelasercanreachashighas150Kbetween25and85°Cduetothe
enhancementofthematerialgain.Calculatedcharacteristictemperatures
areingoodagreementwiththoseobtainedbyexperiment,showingthe
validityoftheresultspresentedhere.[DOI:10.1143/APEX.1.041203]
PhotonicsLaboratories,NTTCorporation,3-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0198,Japan* E-mailaddress:fujisawa@aecl.ntt.co.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.4 (2008) 041301
X-ray Magnetic Circular Dichroism and Photoemission Study of the Diluted Ferromagnetic Semiconductor Zn�-xCrxTeYukiakiIshida1,*,MasakiKobayashi1,Jong-IlHwang1,YukiharuTakeda2,Shin-ichiFujimori2,TetsuoOkane2,KotaTerai2,YujiSaitoh2,YasujiMuramatsu2,AtsushiFujimori1,2,ArataTanaka3,HidekazuSaito4,andKojiAndo4
(ReceivedJanuary28,2008;acceptedFebruary24,2008;publishedonlineMarch21,2008)
WehaveperformedX-raymagneticcirculardichroism(XMCD)and
valence-bandphotoemissionstudiesofthedilutedferromagneticsemi-
conductorZn1-xCrxTe.XMCDsignalsduetoferromagnetismandpara-
magnetismand/or superparamagnetismwereobservedat theCr2p
absorptionedge.Comparisonwithatomicmultipletcalculationssuggests
thatthemagneticallyactivecomponentoftheCrionwasdivalentunder
thetetrahedralcrystalfieldwithtetragonaldistortionalongthecrystal-
linea-,b-,andc-axes.Inthevalence-bandspectra,spectralweightnear
theFermi levelwasstronglysuppressed,suggestingtheimportanceof
Jahn–TellereffectandthestrongCoulombinteractionbetweentheCr
3delectrons.[DOI:10.1143/APEX.1.041301]
1 DepartmentofPhysics,UniversityofTokyo,Bunkyo,Tokyo113-0033,Japan2 SynchrotronRadiationResearchCenter,JapanAtomicEnergyAgency,Sayo,Hyogo
679-5148,Japan3 GraduateSchoolofAdvancedSciencesofMatter,HiroshimaUniversity,Higashihiroshima,
Hiroshima739-8530,Japan4 NanoelectronicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand
Technology(AIST),TsukubaCentral2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:ishida@spring8.or.jp
Appl. Phys. Express Vol.1, No.4 (2008) 041302
Spin-Transfer Switching and Thermal Stability in an FePt/Au/FePt Nanopillar Prepared by Alternate Monatomic Layer DepositionKayYakushiji*,ShinjiYuasa,TaroNagahama,AkioFukushima,HitoshiKubota,ToshikazuKatayama,andKojiAndo(ReceivedFebruary14,2008;acceptedMarch12,2008;publishedonlineApril4,2008)
Wefabricatedacurrent-perpendicular-to-planegiantmagnetore-
sistance(CPP-GMR)nanopillarwitha1-nm-thickFePtfreelayerhaving
perpendicularanisotropyusingthealternatemonatomiclayerdeposition
method.Nanopillarsconsistingof[Fe(1monolayer (ML))/Pt (1ML)]n (n:
thenumberofthealternationperiod)ferromagnetic layersandanAu
spacer layershowedspin-transfer inducedswitchingatroomtempera-
ture.Anaveragecritical switchingcurrentdensity (Jc0)of1.1×107A/
cm2withalargethermalstabilityparameter(Δ)of60wasobtainedina
nanopillarwithafree-layerthicknessof1.02nm(n=3)andapillardiam-
eterof110nm.Theultrathinfree-layerwithhighperpendicularanisot-
ropyiseffectivetoobtainbothlargeΔandsmallJc.
[DOI:10.1143/APEX.1.041302]
NanoelectronicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:k-yakushiji@aist.go.jp
Appl. Phys. Express Vol.1, No.4 (2008) 041501
Reduction of Optical Loss in Hydrogenated Amorphous Silicon/Crystalline Silicon Heterojunction Solar Cells by High-Mobility Hydrogen-Doped In�O� Transparent Conductive OxideTakashiKoida*,HiroyukiFujiwara,andMichioKondo(ReceivedFebruary22,2008;acceptedMarch1,2008;publishedonlineMarch21,2008)
Hydrogen-dopedIn2O3(IO:H)filmswithhighelectronmobilityand
improvednear-infraredtransparencyhavebeenappliedasatransparent
conductingoxide (TCO)electrode inhydrogenatedamorphoussilicon
(a-Si:H)/crystallinesiliconheterojunctionsolarcells.Theincorporationof
IO:H,insteadofconventionalSn-dopedIn2O3,improvedtheshort-circuit
currentdensity (Jsc)and the resultingconversionefficiency.Detailed
opticalanalysisofthesolarcellsrevealedthattheimprovementinJsc is
duetothereductionofreflectionlossattheTCO/a-Si:Hinterfaceand
lessopticalabsorptionintheTCOlayer.[DOI:10.1143/APEX.1.041501]
ResearchCenterforPhotovoltaics,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Central2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:t-koida@aist.go.jp
Appl. Phys. Express Vol.1, No.4 (2008) 041601
Optically Controlled Bimorph Cantilever of Poly(vinylidene difluoride)YasuhiroMizutani,YukitoshiOtani,andNorihiroUmeda(ReceivedFebruary8,2008;acceptedFebruary29,2008;publishedonlineMarch21,2008)
Opticallydrivenactuatorsareanon-contactmethodfortheremote
applicationoflightenergy.Weproposeanewopticallydrivenactuator
thatemploysbimorphpoly(vinylidenedifluoride)(PVDF)cantilevers.PVDF
isaneffectivepolymerfromwhichtoprepareactuatorssinceithasboth
pyroelectricandpiezoelectricproperties.Wehaveproducedabimorph
cantilever fromaPVDFfilmwitha thinAgelectrodeononeside.A
bendingmodelof thePVDFcantileverhasbeenestablishedand its
bendingcharacteristicshavebeenexperimentallymeasured.Themecha-
nismcanbeexplainedbytaking intoconsiderationthemodeland its
dielectricbreakdown.[DOI:10.1143/APEX.1.041601]
TokyoUniversityofAgricultureandTechnology,Koganei,Tokyo184-8588,Japan
Appl. Phys. Express Vol.1, No.4 (2008) 041602
Microstructure Analysis of Solid-State Reaction in Synthesis of BaTiO� Powder Using Transmission Electron MicroscopeKeisukeKobayashi,ToshimasaSuzuki,andYouichiMizuno(ReceivedFebruary13,2008;acceptedFebruary29,2008;publishedonlineMarch21,2008)
Thekineticsandmechanismof thesolid-statereaction inBaTiO3
powder synthesiswere investigatedmicrostructurally.Anequimolar
mixtureofBaCO3andTiO2(rutile)powderscalcinatedat600and800°C
inairwasobservedbyusingtransmissionelectronmicroscopy (TEM).
Duringthereaction, layeredBaTiO3wasformedovertheTiO2particles
withastructurallyandcompositionallysharp interface.Thecrystallo-
graphicorientationrelationshipbetweenTiO2andBaTiO3wasuniversally
observedas[001]TiO2 // [11–0]BTO,(100)TiO2 // (111)BTO.Theperovskitephase
BaTiO3wasformedbyinwarddiffusionofbariumandoxygenionsinto
therutile lattice,maintaininga topotaxial relationshipwith therutile
structure.[DOI:10.1143/APEX.1.041602]
MaterialDevelopmentDepartment,TaiyoYudenCo.,Ltd.,5607-2Nakamuroda,Takasaki,Gunma370-3347,Japan
��JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.4 (2008) 041701
Annealing Effect of �0K-Class Superconductivity of Ca-Doped B�S�CuO�+δ in Bi-��0� PhaseRyozoYoshizaki1,2,*,TetsuyaNakajima1,MasayoshiTange1,**,andHiroshiIkeda1,2
(ReceivedJanuary15,2008;acceptedMarch1,2008;publishedonlineMarch28,2008)
Annealingeffectonmagneticpropertiesof superconductivity is
investigatedforthecrystalsofBi1.9CaySr1.9-yCuO6+δ(0≤y≤1.8)inBi-2201
phase. It is found thatcarrierdensity is reducedwithCadoping in
Ca-poorregionofy≤0.8. Incontrast, theexcessoxygenδ issaturated
withdopingatabout theoptimalTc inCa-richregionofy>0.8.The
resultsindicatepossibleoxygendeficiencieswithCadoping,whichgives
anewaspecttoamodelfortheappearanceof80K-classsuperconduc-
tivity.[DOI:10.1143/APEX.1.041701]
1 GraduateSchoolofPureandAppliedSciences,UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan
2 CryogenicsDivision,ResearchFacilityCenterforScienceandTechnology,UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan
* E-mailaddress:yoshizak@ims.tsukuba.ac.jp**Presentaddress:DepartmentofMaterialsScienceandEngineering,FacultyofEngineering,
IwateUniversity,Morioka020-8551,Japan
Appl. Phys. Express Vol.1, No.4 (2008) 041801
Grain Size Increase and Field-Effect Mobility Enhancement of Pentacene Thin Films Prepared in a Low-Pressure H� AmbientTakamichiYokoyama*,ChangBumPark,KosukeNagashio,KojiKita,andAkiraToriumi(ReceivedFebruary6,2008;acceptedMarch3,2008;publishedonlineMarch21,2008)
Pentacenefilmsweregrownbythermalevaporationindifferentgas
atmospheresatarelatively lowvacuumofabout3Pa,andtheeffects
of thegasambientontheperformanceof thin filmtransistors (TFTs)
were investigated.TheTFTmobilityoffilmdeposited inH2wastwice
thetypicalvalueof0.3cm2/(V·s)forfilmdepositedinvacuum,whilethe
mobilityvaluesoffilmsdepositedinN2andO2werealmostthesame
asthatofvacuum-depositedfilm.Nosignificantchangesinon/offratio,
thresholdvoltage,orhysteresisbehaviorwereobserved inpentacene
TFTspreparedbyevaporationingasambient.Theimprovedmobilityof
pentacenefilmpreparedinH2canbeexplainedbyanincreaseingrain
sizeofthefirstlayerontheSiO2 /Sisubstrate.
[DOI:10.1143/APEX.1.041801]
DepartmentofMaterialsEngineering,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo,Tokyo113-8656,Japan* E-mailaddress:yokoyama@adam.t.u-tokyo.ac.jp
Appl. Phys. Express Vol.1, No.4 (2008) 042001
Photon Correlation in GaAs Self-Assembled Quantum DotsTakashiKuroda1,2,*,MarcoAbbarchi1,3,TakaakiMano1,KenjiWatanabe1,MasakazuYamagiwa1,KeijiKuroda1,KazuakiSakoda1,GiyuuKido1,NobuyukiKoguchi1,CarmineMastrandrea3,LuciaCavigli3,MassimoGurioli3,YoshihiroOgawa4,andFujioMinami4(ReceivedFebruary19,2008;acceptedMarch12,2008;publishedonlineApril4,2008)
Wereportonphotoncoincidencemeasurement inasingleGaAs
self-assembledquantumdot(QD)usingapulsedexcitationlightsource.
Atlowexcitation,whenaneutralexcitonlinewaspresentinthephoto-
luminescence(PL)spectrum,weobservednearlyperfectsinglephoton
emissionfroman isolatedQDat670nmwavelength.Forhigherexci-
tation,multiplePL linesappearedonthespectra,reflectingtheforma-
tionofexcitoncomplexes.Cross-correlationfunctionsbetweenthese
lines showedeitherbunchingorantibunchingbehavior,depending
onwhether therelevantemissionwas fromabiexcitoncascadeora
chargedexcitonrecombination.[DOI:10.1143/APEX.1.042001]
1 NationalInstituteforMaterialsScience,1-1Namiki,Tsukuba,Ibaraki305-0044,Japan2 PRESTO,JapanScienceandTechnologyAgency,4-1-8Honcho,Kawaguchi,Saitama
332-0012,Japan3 EuropeanLaboratoryforNon-LinearSpectroscopy,andDipartimentodiFisica,Universitàdi
Firenze,ViaSansone1,50019,SestoFiorentino,Firenze,Italy4 DepartmentofPhysics,TokyoInstituteofTechnology,O-okayama,Meguro,Tokyo
152-8551,Japan* E-mailaddress:kuroda.takashi@nims.go.jp
Appl. Phys. Express Vol.1, No.4 (2008) 042002
Terahertz-Wave Generation Using a �-Dimethylamino-N-methyl-�-stilbazolium tosylate Crystal Under Intra-Cavity ConditionsTakayukiShibuya1,2,TakuyaAkiba1,KojiSuizu1,HirohisaUchida3,ChikoOtani2,andKodoKawase1,2
(ReceivedFebruary28,2008;acceptedMarch12,2008;publishedonlineApril4,2008)
We succeeded ingenerating terahertzwavesusingdifference-
frequencygeneration (DFG) inanorganic4-dimethylamino-N-methyl-
4-stilbazoliumtosylate(DAST)crystalunder intra-cavityconditions.We
constructedadualwavelengthoutputopticalparametricoscillator(OPO)
withtwopotassiumtitaniumoxidephosphate(KTP)crystalsfortheDFG
pumpingsource,andplacedtheDASTcrystal insidetheOPOcavityto
actasanonlinearwavelengthconversionelement.Ourexperimental
measurementsconfirmedthat intra-cavitygenerationwaspossibleand
thattheoutputlevelwasapproximatelythesameasthatofnormalexci-
tationusingtheexternalOPOoutput.[DOI:10.1143/APEX.1.042002]
1 NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan2 RIKEN,Aramaki-Aoba,Aoba-ku,Sendai980-0845,Japan3 DaiichiPureChemicalsCo.,Ltd.,Koyodai,Ryugasaki,Ibaraki301-0852,Japan
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.4 (2008) 042003
Frequency Increase of Resonant Tunneling Diode Oscillators in Sub-THz and THz Range Using Thick Spacer LayersNaomichiKishimoto1,SafumiSuzuki1,AtsushiTeranishi,1andMasahiroAsada1,2,*
(ReceivedFebruary14,2008;acceptedMarch18,2008;publishedonlineApril11,2008)
Weobtainedfrequencyincreaseofresonanttunnelingdiode(RTD)
oscillatorsusing thick spacer layersat thecollector in sub-terahertz
range.Thisisattributedtoreductionofparasiticcapacitanceduetothe
increaseofspacer layer thickness.Theoscillationfrequency increased
from325to425GHzbythechangeofspacerlayerthicknessfrom5to
45nminreasonableagreementwiththeoreticalcalculation.Frequency
switchingwithbiasdirectionwasalsoobtainedforanRTDhavingan
asymmetric structurewith the thicknessof thecollectorandemitter
spacerlayersof30and5nm,respectively.Theoscillationfrequencywas
394GHzunder forwardbias,whereas336GHzunder reversebias in
whichtheroleoftheemitterandcollectorspacerswasexchanged.
[DOI:10.1143/APEX.1.042003]
1 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,2-12-1-S9-3O-okayama,Meguro-ku,Tokyo152-8552,Japan
2 CREST,JapanScienceandTechnologyAgency,2-12-1-S9-3O-okayama,Meguro-ku,Tokyo152-8552,Japan
* E-mailaddress:asada@pe.titech.ac.jp
Appl. Phys. Express Vol.1, No.4 (2008) 045001
Time-Resolved Investigation of Nanosecond Crystal Growth in Rapid-Phase-Change Materials: Correlation with the Recording Speed of Digital Versatile Disc MediaYoshimitsuFukuyama1,NobuhiroYasuda1,JungeunKim1,HarunoMurayama1,YoshihitoTanaka1,2,ShigeruKimura1,KenichiKato1,2,ShinjiKohara1,YutakaMoritomo1,3,ToshiyukiMatsunaga4,RieKojima4,NoboruYamada4,HitoshiTanaka1,2,TakashiOhshima1,2,andMasakiTakata1,2,5,*
(ReceivedDecember19,2007;acceptedFebruary24,2008;publishedonlineMarch21,2008)
Thecrystallizationprocess indigitalversatiledisc(DVD)mediawas
investigatedusingatime-resolvedX-raydiffractionapparatuscoupled
with in situphotoreflectivitymeasurement.Thetimeprofilesofcrys-
tallizationwere foundtobeconsistentwith thechanges inphotore-
flectivity.Thephasechangeswerecharacterizedbythestartandend
time;90±1and273±1ns forGe2Sb2Te5,and85±1and206±1ns for
Ag3.5In3.8Sb75.0Te17.7, respectively. The faster crystallization time in
Ag3.5In3.8Sb75.0Te17.7isascribedtoitscharacteristiccrystallizationprocess;
itsX-raydiffractionprofileshowsasignificantsharpeningduringthe
crystallizationprocess,whereasthepeakwidthofGe2Sb2Te5remained
unchanged.Thepresentfindingssuggestthatcrystalgrowthcontrol is
anotherkeyfordesigningfasterphase-changematerials.
[DOI:10.1143/APEX.1.045001]
1 JapanSynchrotronRadiationResearchInstitute/SPring-8,1-1-1Kouto,Sayo-cho,Sayo-gun,Hyogo679-5198,Japan
2 SPring-8/RIKEN,1-1-1Kouto,Sayo-cho,Sayo-gun,Hyogo679-5148,Japan3 TheGraduateSchoolofPureandAppliedSciences,UniversityofTsukuba,Tennodai,
Tsukuba,Ibaraki305-8571,Japan4 MatsushitaElectricIndustrialCo.,Ltd.,3-1-1Yagumo-Nakamachi,Moriguchi,Osaka
570-8501,Japan5 DepartmentofAdvancedMaterialsScience,SchoolofFrontierSciences,TheUniversityof
Tokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8561,Japan* E-mailaddress:takatama@spring8.or.jp
Appl. Phys. Express Vol.1, No.4 (2008) 045002
Super-High Brightness and High-Spin-Polarization PhotocathodeXiuguangJin,NaotoYamamoto1,YasuhideNakagawa1,AtsushiMano1,TakanoriKato,MasatoshiTanioku,ToruUjihara,YoshikazuTakeda,ShojiOkumi1,MasahiroYamamoto1,TsutomuNakanishi1,TakashiSaka2,HiromichiHorinaka3,ToshihiroKato4,TsuneoYasue5,andTakanoriKoshikawa5
(ReceivedDecember18,2007;acceptedFebruary29,2008;publishedonlineMarch28,2008)
Usinganewlydevelopedtransmission-typephotocathode,anelec-
tronbeamof super-highbrightness [(1.3±0.5)×107A·cm-2·sr-1]was
achieved.Moreover, the spin-polarizationwasashighas90%.We
fabricatedatransmission-typephotocathodebasedonaGaAs–GaAsP
strainedsuperlatticeonaGaPsubstrateinordertoenhancethebright-
nessandpolarizationgreatly. Inthissystem,alaserbeamis introduced
throughthe transparentGaPsubstrate.Thebeam is focusedon the
superlatticeactive layerwitha short focal length lens.Excitedelec-
tronsaregeneratedinasmallareaandextractedfromthesurface.The
shrinkageoftheelectrongenerationarea improvedthebrightness. In
addition,aGaAslayerwasinsertedbetweentheGaPsubstrateandthe
GaAsPbufferlayertocontrolthestrainrelaxationprocessintheGaAsP
buffer layer.Thisdesign for straincontrolwaskey inachievinghigh
polarization(90%)inthetransmission-typephotocathode.
[DOI:10.1143/APEX.1.045002]
GraduateSchoolofEngineering,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan1 GraduateSchoolofScience,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8602,
Japan2 ElectricalandElectronicsEngineering,DaidoInstituteofTechnology,10-3Takiharu-cho,
Minami-ku,Nagoya457-8530,Japan3 GraduateSchoolofEngineering,OsakaPrefectureUniversity,1-1Gakuen-cho,Naka-ku,
Sakai599-8531,Japan4 DaidoSteelCo.,Ltd.,2-30Daido-cho,Minami-ku,Nagoya457-8545,Japan5 FundamentalElectronicsResearchInstitute,AcademicFrontierPromotionCenter,Osaka
Electro-CommunicationUniversity,18-8Hatsu-cho,Neyagawa,Osaka572-8530,Japan
Appl. Phys. Express Vol.1, No.4 (2008) 045003
Self-Separation of a Thick AlN Layer from a Sapphire Substrate via Interfacial Voids Formed by the Decomposition of SapphireYoshinaoKumagai1,*,JumpeiTajima1,MasanariIshizuki1,2,ToruNagashima3,HisashiMurakami1,KazuyaTakada3,andAkinoriKoukitu1
(ReceivedMarch4,2008;acceptedMarch21,2008;publishedonlineApril11,2008)
AtechniqueforseparatingathickAlNlayergrownbyhydridevapor
phaseepitaxy(HVPE)ona(0001)sapphiresubstratewasdeveloped.By
heattreatmentat1450°CinagasflowcontainingH2andNH3,many
voidscouldbeformedattheinterfacebetweenathin(100nm)AlNlayer
grownat1065°Candthesapphiresubstratedueto thepreferential
decompositionofsapphire.Duringthecoolingprocessafterthesubse-
quentgrowthofathick(85µm)AlNlayer,thethickAlNlayerseparated
fromthesapphiresubstratewiththeaidof the interfacialvoids.The
freestandingAlNsubstratethusobtainedhadasmooth(0001)surface,
adislocationdensityof1.1×109cm-2,andanoptical transparencyfor
wavelengthsabove208.1nm.[DOI:10.1143/APEX.1.045003]
1 DepartmentofAppliedChemistry,GraduateSchoolofEngineering,TokyoUniversityofAgricultureandTechnology,2-24-16Naka-cho,Koganei,Tokyo184-8588,Japan
2 ResearchandDevelopmentDivision,TokuyamaCorporation,ShibuyaKonnoBldg.,3-3-1Shibuya,Shibuya-ku,Tokyo150-8383,Japan
3 TsukubaResearchLaboratories,TokuyamaCorporation,40Wadai,Tsukuba,Ibaraki300-4247,Japan
* E-mailaddress:4470kuma@cc.tuat.ac.jp
�0JSAPInternationalNo.18(July2008)
Appl. Phys. Express Vol.1, No.4 (2008) 045004
Determination of the Twist Angle of GaN Film by High Resolution X-ray DiffractionHongtaoLi,YiLuo*,LaiWang,GuangyiXi,YangJiang,WeiZhao,andYanjunHan(ReceivedMarch5,2008;acceptedMarch21,2008;publishedonlineApril11,2008)
Asanazimuthalscanmethod,ϕ-scanspreformedbyX-raydiffrac-
tionareusuallyusedtodeterminethetwistangleinGaNfilms.However,
bothtwistandtiltcontributetofullwidthathalfmaximum(FWHM)of
ϕ-scancurves.Sofarnomodelhasbeenproposedtodistinguishthe
contributionsoftiltandtwisttoFWHMofthesecurves.Ageometrical
modelispresentedtodistinguishtheircontributions,whichisveryimpor-
tanttopreciselydeterminethedislocationdensitiesinGaN.Basedonthis
model,FWHMofϕ-scanscanbeexpressedasasimpleexplicitfunction
oftheoriginaltwistangleandanadditionaltwistangleinducedbytilt.
Thesetwistanglesarethensimplyandeffectivelydeterminedforvarious
GaNfilmsaccordingtothissimplefunction,andareingoodagreement
withthosededucedfromω-scandatafitting.
[DOI:10.1143/APEX.1.045004]
StateKeyLaboratoryonIntegratedOptoelectronics/TsinghuaNationalLaboratoryforInformationScienceandTechnology,DepartmentofElectronicEngineering,TsinghuaUniversity,Beijing100084,China* E-mailaddress:luoy@tsinghua.edu.cn
Appl. Phys. Express Vol.1, No.4 (2008) 046001
Gas-Temperature-Dependent Characteristics of Cryo-Dielectric Barrier Discharge Plasma under Atmospheric PressureYuriNoma,JaiHyukChoi,SvenStauss,TakaakiTomai,andKazuoTerashima(ReceivedJanuary21,2008;acceptedMarch7,2008;publishedonlineMarch28,2008)
Inthepresentwork,cryo-dielectricbarrierdischarge(DBD)plasma
wasgeneratedcontinuouslybelowroomtemperaturedownto liquid
nitrogentemperature (296to78K)underatmosphericpressureusing
parallel indium –tin-oxide (ITO)-coatedelectrodes.Gas-temperature-
dependentoptical emission spectroscopy (OES)measurementsand
dischargepatternobservationofcryo-DBDplasmawereperformed. In
thecaseofheliumgas,thedischargemodeofcryo-DBDplasmachanged
fromfilamentarymodetoglowmodeasthegastemperaturedecreased.
Whenintroducingasmallamountofnitrogen inheliumgas, thefila-
mentarydischargemodepersistedupondecreasingthegastemperature,
althoughthedischargepatternchangedfromconcentricrings(296K)to
ahexagon-likepattern(78K).[DOI:10.1143/APEX.1.046001]
DepartmentofAdvancedMaterialsScience,GraduateSchoolofFrontierSciences,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba227-8561,Japan
Appl. Phys. Express Vol.1, No.4 (2008) 046002
Discharge Characteristics of Microwave and High-Frequency In-Liquid Plasma in WaterShinfukuNomura,HiromichiToyota,ShinobuMukasa,YoshiyukiTakahashi,TsunehiroMaehara,AyatoKawashima1,andHiroshiYamashita(ReceivedJanuary31,2008;acceptedMarch12,2008;publishedonlineApril4,2008)
Theplasmainwater isgeneratedbyapplyinghigh-frequency(HF)
irradiationof27.12MHzormicrowave(MW)radiationof2.45GHzfrom
anelectrode.TheelectrodeisheatedbyjouleheatingbytheHForMW
irradiation,andvaporbubblesaregeneratedsimultaneously.Theplasma
isthenignitedinsidethebubblesontheelectrode.Theglowdischarge
plasmacanbemaintainedinspiteofatmosphericpressureduetothe
coolingeffectoftheliquiditself.Theelectrontemperatureoftheplasma
generatedbythe27.12MHzradiationishigherthanthatgeneratedby
the2.45GHzradiation.[DOI:10.1143/APEX.1.046002]
GraduateSchoolofScienceandEngineering,EhimeUniversity,3Bunkyo-cho,Matsuyama790-8577,Japan1 DepartmentofEnvironmentalScienceforIndustry,EhimeUniversity,3-5-7Tarumi,
Matsuyama790-8566,Japan
Appl. Phys. Express Vol.1, No.4 (2008) 047001
Enhancement of Acid Production in Chemically Amplified Resist for Extreme Ultraviolet LithographyHirokiYamamoto,TakahiroKozawa*,SeiichiTagawa**,HirotoYukawa1,MitsuruSato1,andJunichiOnodera1
(ReceivedNovember27,2007;acceptedFebruary29,2008;publishedonlineMarch21,2008)
Thetrade-offamongsensitivity,resolution,andlineedgeroughness
(LER)isthemostseriousproblemfortherealizationofextremeultraviolet
(EUV)lithography.Asolutiontothisproblemistheenhancementofacid
generationefficiencyperunitvolume.InchemicallyamplifiedEUVresists,
nottheacidgeneratorsbutthepolymermainlyabsorbsEUVphotons.
ThesecondaryelectronsgeneratedbyEUVabsorptionsensitizetheacid
generators.Therefore,anincreaseinthepolymerabsorptioncoefficient
isexpectedtoleadtotheenhancementofacidproduction.Theincor-
porationof fluorineatoms isapromisingwayfor the increase in the
absorptioncoefficientofEUVresists.However,fluorinatedcompounds
decreasetheacidgenerationefficiencybyinterferingwiththereaction
ofacidgeneratorswith low-energyelectrons.We investigatedwhich
effectprevails inacidgeneration.Usingaspectroscopicmethod,itwas
confirmedthattheincorporationoffluorineatomsleadstoanincrease
inacidgenerationefficiencyperunitvolume.
[DOI:10.1143/APEX.1.047001]
TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 TokyoOhkaKogyoCo.,Ltd.,1590Tabata,Samukawa,Koza,Kanagawa253-0114,Japan* E-mailaddress:kozawa@sanken.osaka-u.ac.jp**E-mailaddress:tagawa@sanken.osaka-u.ac.jp
Applied Physics Express
JSAPInternationalNo.18(July2008)��
Appl. Phys. Express Vol.1, No.4 (2008) 047002
Organic Contaminant Detection of Silicon Wafers Using Negative Secondary Ions Induced by Cluster Ion ImpactsKouichiHirata*,YuichiSaitoh1,AtsuyaChiba1,andKazumasaNarumi2(ReceivedJanuary24,2008;acceptedMarch7,2008;publishedonlineMarch28,2008)
Emission yields of carbon and hydrogenated carbon cluster
secondaryionsCpHq±(p≥1,q≥0)originatingfromorganiccontaminants
onasiliconwaferarecomparedbetweenmonoatomic(0.5-MeV/atom
C1+)andcluster ion (0.5-MeV/atomC8
+) impactsusingtime-of-flight
(TOF)secondaryionmassspectrometry.CpHq-fortheclusterionimpact
exhibitsthehighestemissionyieldperincidentatomamongCpHq±with
thesamepnumber.ThehighestrelativeCpHq-emissionyield for the
clusterionimpactreaches~20and~60timeshigherincomparisonwith
thoseofCpHq-andCpHq
+withthesamepnumberforthe impactof
themonoatomicionwiththesamevelocity,respectively.Combinationof
negativesecondaryionTOFmeasurementswithclusterimpactionization
isapromisingtoolforhighlysensitivedetectionoforganic-contaminants
onsiliconwafers.[DOI:10.1143/APEX.1.047002]
NationalMetrologyInstituteofJapan,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Tsukuba,Ibaraki305-8565,Japan1 DepartmentofAdvancedRadiationTechnology,TakasakiAdvancedRadiationResearch
Institute(TARRI),JapanAtomicEnergyAgency(JAEA),Takasaki,Gumma370-1292,Japan2 AdvancedScienceResearchCenter,JapanAtomicEnergyAgency(JAEA),Takasaki,Gumma
370-1292,Japan* E-mailaddress:k.hirata@aist.go.jp
Appl. Phys. Express Vol.1, No.4 (2008) 049201
Erratum: “Local Synthesis of Tungsten Oxide Nanowires by Current Heating of Designed Micropatterned Wires”KeisukeNagato1,2,*,YusukeKojima1,KeigoKasuya3,HirokiMoritani1,TetsuyaHamaguchi1,andMasayukiNakao1
(ReceivedJanuary29,2008;acceptedMarch11,2008;publishedonlineMarch28,2008)
[DOI:10.1143/APEX.1.049201]
1 DepartmentofEngineeringSynthesis,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan
2 ResearchFellowoftheJapanSocietyforthePromotionofScience,8Ichibancho,Chiyoda-ku,Tokyo102-8472,Japan
3 CentralResearchLaboratory,Hitachi,Ltd.,1-280Higashi-koigakubo,Kokubunji,Tokyo185-8601,Japan
* E-mailaddress:nagato@hnl.t.u-tokyo.ac.jp
top related