present status and future prospect of the power
TRANSCRIPT
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Beijing University Semimar
Present Status and Future Prospect ofthe Power Electronics Based on
Widegap Semiconductors
National Institute of Advanced Industrial Science & Industry
Power Electronics Research Center
Hajime Okumura
2007.11.22
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
o MITI(Ministry of International Trade and Industry)
AIST(Agency of Industrial Science and Technology)
…
…
Electrotechnical laboratory(ETL)
…
…
Establishment of New AIST(Re-organization of Japanese National Institutes)
(15 Institutes)(56 Research Units)
o METI(Ministry of Economy, Trade and Industry)
AIST(National institute of Advanced Industrial Scienceand Technology)
…
Power Electronics Research Center(PERC)Widegap Semiconductor Electronics
…
9 research bases and 2 headquarters
(3200 permanent staffs)
http://www.aist.go.jp
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Organization of new AIST
Research Facilities Dept.
Financial Affairs Dept.
Human Resource Dept.
General Administration Dept.
Int. Affairs Dept.
Public Relation Dept.
AIST Innovations (TLO)
Collaboration Dept.
Technology Information Dept.
AIST Innovation Center for Start-ups
Int. Patent Organism Deposaitry
Tsukuba Advanced Computing Center (TACC)
2 Special Divisions (AIST Kansai) ........ ........
12 Research Initiatives ........ ........ ........
27 Research Centers ........ ........ Power Electronics Research Center (PERC) ........ ........
21 Research Institutes ........ ........ ........ ........
Research Coordinator
Superintendent
Planning Headquarters
General AdministrationHeadquarters
Evaluation Dept.
Safety and EnvironmentalProtection Dept.
AIST Advisory board
AIST fellow
Auditor
PresidentVice-PresidentTrustee
9 Research Bases AIST Hokkaido AIST Tohoku AIST Tsukuba AIST Tokyo Waterfront AIST Chubu AIST Kansai AIST Chugoku AIST Shikoku AIST Kyushu
2003.3
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Mission and Activity Area
Mission(a) Industrial infrastructure technology, including measurement standards, geological
surveys, and the development of base technologies necessary for the maintenance of thetechno-infrastructure of Japan.
(b) Energy and environmental technology, which because of long lead times and highrisk require the government to search for solutions.
(c) Interdisciplinary and broad-spectrum research activities to promote innovation andreinforce the international competitive strength of Japanese industry and encourage thecreation of new industries.
Activity (Research Fields)(1) Life Science and technology
(2) Information Technology
(3) Environment and Energy
(4) Nanotechnology, Materials and Manufacturing
(5) Geological Survey and Geoscience, Marine Science and Technology
(6) Standards and Measurement Science and Technology
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Research Scheme and FundSubsidy from METI,
Entrustment from METI,
Entrustment from other ministries,
Subsidy or entrustment from public research funding
organizations such as NEDO, JST
Entrustment from or collaboration with private
companies
Trend of recent governmental fund• Industrialization,• Collaboration of Univ., National Inst. and
Private Sector
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Mission of PERC
Development of the electronics based on widegap
semiconductor materials and science,
Application of the related technology to actual information
and energy networks in the human society, in order to
contribute to the innovation of life line and energy saving
Teams of PERC1. Wafer & Characterization Team SiC bulk & epitaxial growth, wafer characterization2. SiC Power Device Team SiC device technology3. GaN Power Device Team III-Nitride device technology4. Power-Unit Super-Design Team Design & simulation of power devices and modules5. Super-Node Network Team Networking technology using low-loss power devices6. Advanced power electronics promotion team Industrialization of power device technology
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Contents
1. Importance of wireless communication,power electronics in the 21th century
2. Requirements from system application tohigh-power electron device
3. Characteristics of widegap semiconductors
4. High-power operation by widegap semiconductor devices
5. Present R&D status of high-power electron devices
6. Problems and future prospectSiC devices or GaN devices ?
Electron devices (high-power)
•High-frequency device (analog appl.)
•Switching device (digital appl.)
•SiC
•III-nitrides
Widegap semiconductors
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
21th century
networking
freightEV/HEV
Nest-generation
transportation
InformationInternet
Wireless communication
Computer
Man-machine interface
EnergyCooperation between
large scale generators
and dispersed generators
Electronics
Innovative high-power device
networking
Infrastructure of the 21th century
Information Electronics Energy Electronics
Environment Energy utilization Economic Growth
Energy
saving
Industry Convenience
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Fixed Wireless CommunicationWireless Terminal Access
FWA, LMDS, WLL)Mobile CommunicationMobile Telephone System
Communication betweenBase Stations
PrincipalBackbone System
Home NetworkWireless LAN
Satellite CommunicationSatellite BroadcastingGround Broadcasting
Intelligent Transportation System (ITS) -- VICS, ETC
Various applications ofwireless communication
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
2nd gen. (Digital cellular)
Quasi-Linear region
multi-carrier common amp.
200W/sector
Trend of Power FET Specificationfor Mobile Telephone Base Station
In Out
Common amplification
of multi carriers
3rd gen. (Total Digital Service)
Strict Linear region
W-CDMA IMT-2000
500W 1kW/sector
1st gen. (Analog cellular)
Saturated region is enough
Strict Linear
Ou
tpu
t P
ow
er
(d
Bm
)
Quasi- Linear
Saturated
Input power (dBm)
Po
wer
Ad
ded
eff
icie
ncy (
%)
Keeping Transmission distanceEnlarging band width (Channel number)Keeping Linearity Higher Power
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Energy Consumption and Electricity Ratio
0
50000
100000
150000
200000
250000
300000
350000
400000
10
15
20
25
30
1965 1970 1975 1980 1985 1990 1995 2000
(%)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Energy Saving in Electric Power
Application of Electronics to the control of Electric Power (Energy Electronics, Power Electronics) High Voltage, Large Current
Urgent issue, considering Electricity Ratio
Application Field of Power Electronics
Power Conversion(AD/DA conversion
Inverter circuit
Power Device(Transistor)
Operating Frequency (kHz)
Pow
er C
onve
rsio
n C
apac
ity
(kV
A)
Application fields
of WGS FETs
Thyristor
Power ICs
GTO
MOSFET
HVDCMachines
Railways
Switching regulators
VTRs, Mobile phonesTelephone exchangers,PDP drivers
0.1 1 10 100 1000
EVs/HEVs
104
103
102
101
100
105
IGBT
Motors, InvertersAir conditioners
UPSsDistgributed power supplies
Bipolartransistor
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Example of Power device usagein Electric Power Converter
Device chips with small
size and low resistance
Device modules with small
size and higher operation
frequency
Simple and small peripherals
Innovation of
Power Electronics
Key of Energy saving
technology
in Electric Power
What is an ideal switch ?on-state zero resistance
off-state resistance infinity
Motor
(20kW)
Battery
EB=350V
IGBT
IGBT
SBD
SBD
DC48V
100A
DC/AC inverter
DC/DC converter
FET
Electrical switch (Switching device)
Blocking voltage and conduction loss (onresistance) show a trade-off relation
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
(a): Switching Power Supply (b): Motor Drive Inveter
Analysis of Power Loss in TypicalElectric Power Converters
Components of loss
Power devices Passive elements 60% : 40%
Lidow, et.al, Proc. of IEEE, 89, 803 (2001)
Capacitor
30%
Inductor
10%
Synchronous rectifying FET: 23%
Control FET
36%
Other
%IGBT/FRD
46%
Rectifying diode : 16%
Coil
10%
Control
7%
SMPS
12%
Capacitor 9%
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Device Specification Requirementsfrom Application Needs
1. High frequency: Enlarged frequency domain,
large-capacity high-speed communication,
broad band
2. High output power long-distance transmission
broad band, low distortion
3. High operation voltage high-efficiency, low-loss, small size
High-frequency devices for wireless communication
1. High blocking voltage applicability, reliability
2. Low on-resistance reduction of conduction loss
3. High switching speed small size
4. Low electrostatic capacity reduction of switching loss, high-speed switching
5. High tolerance reliability, safety
Switching devices for power electronics
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
What is WidegapSemiconductors ?
C : Carbides IV-IV group IV-IV group polytypespolytypes MOS structureMOS structure Indirect band structure Indirect band structure
N : Nitrides III-V group III-V group Hetero Hetero sturucturesturucture AlloysAlloys Direct band structure Direct band structure
O : Oxides II-VI group II-VI group Insulator to Superconductors Insulator to Superconductors
Light Element SemiconductorsLarge binding energyHigh melting pointSmall lattice constant
LargeBandgapThermal conductivityBreakdown voltageSaturation drift velocitythermal and chemical stability
Hard ElectronicsHigh temperature devicesHigh power devicesHigh frequency devices Short wavelength devices
Si
Ge
Sn
Al
Ga
In
P
As
Sb
S
Se
Te
Mg
Zn
Cd
2
3
4
5
B C N O
III IV V VI
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Lattice Constants and Bandgap
c-BN
h-BN
��������
AlN
3C-SiC
6H-SiC4H-SiC
15R-SiC
BP
GaN
ZnO
BAs
InN
Si
AlP
c-ZnS
GaP
h-ZnS
Ge
AlAs
GaAs
ZnSe HgSCdS
InP
HgSe
CdSeZnTe
InAs
GaSb
SnInSb
CdTe
HgTe
2H-SiC
MgS
MgSe
0
2
4
6
8
1.5 2.0 2.5 3.0
Ban
dgap
(eV
) -
R.T
.
Diamond
Bond Length (Å)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Physical Properties ofSemiconductors
Material Eg μ Ec sat band typeeV cm2/Vs 106V/cm 107cm/s W/cmK
Si 1.1 11.8 1350 0.3 1.0 1.5 IGaAs 1.4 12.8 8500 0.4 2.0 0.5 D
c-GaN 3.27 9.9 1000 1 2.5 1.3* Dh-GaN 3.39 9.0 900 3.3 2.5 1.3 D3C-SiC 2.2 9.6 900 1.2 2.0 4.5 I6H-SiC 3.0 9.7 370a, 50c 2.4 2.0 4.5 I4H-SiC 3.26 10 720a, 650c 2.0 2.0 4.5 I
AlN 6.1 8.7 1100 11.7 1.8 2.5 DDiamond 5.45 5.5 1900 5.6 2.7 20 I
a: along a-axis, c: along c-axis, *: estimate
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Figures of Merits of Several Semiconductorsand their Hetrostuructures
Material Johnson’s FM Keyes’s FM Shenai’s FM(QF1) Shenai’s FM(QF2) Baliga’s FM Baliga’s HFM
(Ec sat/ )2 ( sat/ )1/2A AEc μEc
3 μEc2
Si 1 1 1 1 1 1GaAs 7.1 0.45 5.2 6.9 15.6 10.8
c-GaN 685 1.5 20 67 23 8.2h-GaN 760 1.6 560 6220 650 77.83C-SiC 65 1.6 100 400 33.4 10.36H-SiC 260 4.68 330 2670 110 16.94H-SiC 180 4.61 390 2580 130 22.9
AlN 5120 21 52890 2059000 31700 1100Diamond 2540 32.1 54860 1024000 4110 470
A=Shenai’s FM(QF3)=_ μEc3 T.P. Cho, Materials Science Forum, Vols. 338-342 (2000) 1155.
SH-HEMT on GaAs DH-HEMT on GaAs P-HEMT on InP GaN-HEMT on sapphire
μ (cm2/Vs) 5000 � 6500 5000 � 6500 9500 � 12000 800 � 1700
ns (1012/cm3) 1.5 � 2.5 2.0 � 3.0 3.0 � 4.0 15 � 20
ns μ (1015/Vs) 7 � 16 10 � 20 30 � 50 12 � 34
Rch ( /sq) 400 � 600 300 � 500 150 � 250 200 � 520
By H. Kawai
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Saturation Drift Velocity &Breakdown Voltage vs. Electric Field
High Breakdown Voltage
High Drift Velocity
Saturation at High Field
50 100 150 200 250 3000Electric Field (kV/cm)
Vel
ocit
y (1
07cm
/s)
1
2
3
0
GaN
InP
Si
GaAs
Characteristics of GaN
Dri
ft v
eloc
ity
(10
cm
/s)
7
High Voltage operation ispossible even aftermicrointegratioin
Suitable for high-powerhigh-frequency operation
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Properties of Wide BandgapSemiconductor Devices
Breakdown Voltage (V)100 1000 10000
100
1
0.01
0.0001On
Res
ista
nce
( c
m2 )
Si6H-SiC
4H-SiCGaN
Diamond
On resistance andBreakdown Voltage
Temperature dependence ofp-n junction leak current
100
10-2
10-4
10-6
1.0 1.5 2.0 2.5
Si
GaAs
6H-SiC
GaN
Diamond
1000/Temperature (1/K)
Lea
k C
urre
nt
Den
sity
(/c
m2 )
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Applied electric field
Structures of High-Power Electron Device
n+ substrate
n- epilayer
n+
p+p+
drain
sourcegate
n+ substrate
n- epilayer
n+ n+
p+ p+
drain
gatesourceOxide
JFETJunction field Effect
Transistor
MOSFETMetal Oxide Semiconductor
Field Effect Transistor
p+ substrate
n- epilayer
n+ n+
p+ p+
drain
gatesourceOxide
IGBTInsulated Gate
Bipolar Transistor
Unipolar deviceBipolar device
drain
Semi-insulating substrate
Highly resistive buffer
Barrier
source gate
n- epilayer
- - - -
n+n+
HFETHeterojunction
Field Effect Transistor
Vertical deviceLateral device
2DEG channel
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Under Class A amplification,Pout = (1/8) (VB-Vknee) Imax
Imax ns μ
VB EC
Under Imax=1A/mm, VB=80V (Vsd=40V), and Wg=20mm,
Pout=10W/mm and Ptotal=200W are obtained.
Vd
IdImax
VBVknee
Load line
Vg
Input signal
High-power operation of HF device
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
10-1
100
101
102
103
1G 10G 100GFrequency (Hz)
Thermal LimitMaterial Parameter Limit
Current Gain Limit
P fT vs Ec1 2
3P fT2 Constant
Ave
rage
Pow
er (
W)
Operation limit ofHigh-Frequency Devices
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Out
put
Pow
er D
ensi
ty (
W/m
m) 100
10
1
0.1
0.011 2 3 5 7 10 20 30 50 70 100
Drain Voltage (V)
GaN HFET / SiC
GaN HFET / sapphire
GaAs MESFET
4H-SiC MESFET
6H-SiC MESFET
�
�
�
��
���
�
��
�
����
��
��
�: 4H SiC MESFET
�: GaN HFET / sapphire
�: Si-LDMOSFET�: GaAs MESFET
�: SiC-SIT.
: GaN HFET / SiC.
�: 6H-SiC MESFET
�
��
�
Operation Voltage and Power Densityof High-Power HF devices
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
0.1
1
10
100
1000
4åé/1 4åé/1 4åé/1 4åé/1 4åé/1 4åé/1 4åé/1
Tol
tal
Out
put P
ower
(W)
Calendar yearApril, '00 April, '02 April, '04 April, '06
2GHz band>20GHz
0.1
1
10
100
1000
1 10 100
Out
put
Pow
er /
Chi
p (
W)
Frequency (GHz)
GaN-related devicesGaAs-related devicesInP-related devices
(a) (b)
R&D Status of high-power HF devices
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Comparison of Depletion Layer Expansionand Electric Field in a Switching Device
On-Resistance
RDS = WD (q nND)
= 4VB2 ( nEC
3)
Blocking Voltage
VB= (ECWD) 2
Carrier Density
ND = ( /q) (EC/WD)
= 2 EC2 qVB
Ele
ctri
c fi
eld
Position in drift layer
ND(Si) dE(x)/dx
ND(WGS) dE(x)/dx
EC(WGS)
0
EC(Si)
WD(Si)WD(WGS) x
V= E(x) dx
E(x)
p+
Depletion layerWGSVB
Junction edge
p+
n+n-
Drift layer
n- n+
VB
Si
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Performance Indices of Power Switching Devices
10-2
10-1
100
101
102
101 102 103 104
On-
Res
ista
nce
Vlocking Voltage VB
RDS
for Si
RDS
for 4H-SiC RDS
for GaN
Ron
for 4H-SiClimited by R
ch and R
c
Rch
and Rc
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
R&D Status of Low-Loss Swtching Devices --- Fabrication Trials and Simulation ---
10-2
10-1
100
101
102
101 102 103 104
Spec
ific
On-
Res
ista
nce
(m c
m2 )
Blocking Voltage (V)
Si MOSFET 4H-SiC MOSFET 4H-SiC JFET/SIT GaN HFET GsN MISHFET
Si Unipolar Limit
GaN Unipolar Limit4H-SiC Unipolar Limit
GaN lateral FET
4H-SiC lateral FET
Diamond lateral FET
Limit by μch
=20cm2/ V s
Limit by μch
=200cm2/ V s
SiC IGBTSiC GTO
Si IGBT
Breakdown Voltage VB (V)
100 1k 10k0.1
1
10
100
Sp
ecif
ic O
n-R
esis
tan
ce R
on (
mcm
2)
Si-limit 4H-SiC-limit
GaN-limit
4H-SiC-LFET
GaN-LFET
Diamond-LFET
By W. Saito (Toshiba)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Blocking Voltage and On-Resistance of GaN HFET
High blocking voltage HFET
0
0.005
0.01
0.015
0.02
0 400 800 1200 1600
Id-Vd
Dra
in C
urr
ent
[A]
Drain Voltage [V]
Vg = +2 V
Vg = 0 V
Vg = -2 V
Vg = -5 V
SiN : 5nm
Lg = 4 μm
Lsd = 34 μm
S. Yagi et al.: Solid-StateElectron. 50 (2006) 1057.
Lsd (μm)
Source-Drain distance dependence of on-resistance
M. Inada et al. : Proc. Int. Symp.Power Semicond. Devices & ICs,Naples, 2006, p.121.
Low on-resistance HFET
: 1.7kV
: 0.088m cm2
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
R&D trend of Current Capacityon SiC Devices
‘04‘02‘00‘98‘96‘940.1
1
10
100
1000C
urr
ent
Cap
aci
ty/C
hip
(A)
Cree
CreeSiCED
Cree & Auburn
Cree
SiCED
SiCED
Denso
‘06
Mitsubishi
Hitachi
Hitachi
SiCED
SiCED
SiCED
Toshiba
CRIEPI
Rutgers Univ.
CreeSiCED
SiCED
SiCED
SiCLAB
Cree
ABBCree
TDI(USA)
SiCLAB
Rockwell
Daimler
Cree
PiN
SBD
MOSFET
JFET(SIT)
Years
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Recent Results of Device/Inverter R&D (1)
Mitsubishi Electric (2006.1.24)1. Module by 1200V, 10A MOSFETs (On-resistance :10m cm2
2. Inverter operation of a 3.7kW motor (SiC-MOSFET+SiC-SBD3. 54% reduction of a inveter loss (vs. Si-IGBT inverter)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Recent Results of Device/Inverter R&D (2)
Kansai Electric Power & Cree Inc. (2006.1.25)1. 4.5 kV, 100 A SiC Commutated Gate Turn-off Thyristor (SiCGT)
8x8mm2
2. 110kVA 3-phase inverter SiC-MOSFET+SiC-PiN Dwithout snubber circuit, operation at 300˚C
3. Reduction of inverter loss by more than 50% (vs. Si-IGBT inverter)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
From Crystal to Application System
Device chips
MOSFET, SBD etc.
Ion Implantation
Dry etching
Metallization
RTA
Device modulesDicing
Bonding
mounting
Bulk waferSlice, wrapping
Circuit mounting
Epitaxial waferEpitaxial growth
0 1μm
2-inch
100μm
0 1μm
0
1nm
0.5nm
Gate
Source
Active area
200x200μm2
SiC powderIngot
sublimation
HP
Inverters
HP
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Problems in Widegap Semiconductor Device Technology
III-Nitrides SiC
Self-heating, Thermal mounting
Channel mobility
Gate Leakage (degradation of VB, efficiency)
Current Collapse (Insulator, surface/interface control
Normally-off operation
Reliability (Oxide interface)
Tolerance (Avalanche/Short-circuit capability)
Wafer Quality
Surface Morphology
High Al content
Purification of channel layer
Highly resistive buffer layer
Reduction of off-angle
Polarity control
p-type control
Uniformity in a wafer (thickness, doping, content)
Dislocation, defects in epitaxial layers
Bulk wafer
Defect ControlDevice killer defects
Device structures
Module structures
Manufacturing TechnologyLarge size, multi-wafer
Uniformity, reproducibility
III-Nitrides SiC
Self-heating, Thermal mounting
Channel mobility
Gate Leakage (degradation of VB, efficiency)
Current Collapse (Insulator, surface/interface control
Normally-off operation
Reliability (Oxide interface)
Tolerance (Avalanche/Short-circuit capability)
Wafer Quality
Surface Morphology
High Al content
Purification of channel layer
Highly resistive buffer layer
Reduction of off-angle
Polarity control
p-type control
Uniformity in a wafer (thickness, doping, content)
Dislocation, defects in epitaxial layers
Bulk wafer
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Enlargement of SiC Wafer Size and Defects
25mm30mm
35mm
50mm
75mm
100mm
1992 1993 1994 1995 1996 1997 1998 1999 2000
Sublimation Method
X-Ray Topography Micro-pipesW
afer
Siz
e
Calendar Year
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Comparison of SiC Single Crystal Wafer
C Corp. (2 inch)
MPD 15/cm2
C Corp. (3 inch)
MPD 5/cm2
B Corp. (2 inch)
MPD 5/cm2
A Corp. (2 inch)
MPD 30/cm2
MP Almost solved
Dislocation Killer defects
determining device performance
Threading Dislocation (Screw, Edge)
Basal Plane Dislocation
Distortion of crystal planes
(Thermal distortion)
EPD
4 inch
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Shee
t R
esis
tanc
e (
/)
300
400
500
600
700
800
900
0.15 0.20 0.25 0.30 0.35
Al Content of AlGaN Barrier layer
Al Content and Sheet Resistance of an
AlGaN/GaN Heterostructure Wafer
GaN
AlxGaN1-xN
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Surface morphology of high Al-contentAlGaN epitaxial layer
sub (RMS 0.2nm)
GaN epi-layer(RMS 0.3nm)
3nm
0nm
3nm
0nmquasi-Al0.5Ga0.5N(RMS 0.2nm)
3nm
0nm
Al0.5
Ga0.5
N(RMS 1.4nm)
5nm
0nm
AlGaN/GaN
(0.2<x<0.6)
GaN
AlxGa
1-xN
GaN(2 m)
Al2O3
2 (AlN/GaN)n/GaN
GaN
AlNGaN
GaN
GaN(2 m)
Al2O3
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Al-content(equivalent) dependnceof Sheet resistance
Realization of
Lowest value
170 /
AlGaN alloy
quasi AlGaN
AlGaN alloy (ref.)
0
200
400
600
800
1000
0 10 20 30 40 50 60 70 80
(equivalent) Al composition [%]
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
•Recess gate structure
•Introduction of fixed charge
•MOS structure
•Utilization of non-polar surface
•pn-junction gate
•GaN Cap layer
•Asymmetry AlGaN/GaN/AlGaN channel
Normally-off operation ofGaN switching devices
Existing Gate drive circuit
incompatibility of control power supply, gate signal
Care for Power supply circuit (Safety)
Trials by various approach
Confirmation of necessity ?
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Examples of Normally-off operation
Ron
A = 2.6m cm2, Idmax
= 200mA/mm
pn-junction gate
Y. Uemoto et al.,
IEDM2006, San Francisco,
USA (2006.12)
recess gate with
high-k insulator
H. Sazawa et al., IWN2006,
Kyoto, Japan (2006.10)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Important Technical Issuefor the Realization of WGS Inverters
• micropipe
• dislocation SD, ED, BPD etc.
• Grain boundary, oxide interface
• Channel mobility
• Blocking voltage, current leakage
• Reliability
(correlation between wafercharacteristics and device performance)
Characterization Techniques/Tools
Reflection X-ray topograph
image for a SiC SBD
threading screw 39 ( 3900 cm-2 )
threading edge 126 ( 12600 cm-2 )
basal plane 20 ( 200 cm-2 )
There remain many unknown factors in WGS Physics
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Required specification for voltage and current,
relation with the density of device killer defects
2002 2010 202004 0806
1000
100
10
1
10
1
0.1
5.0kV,100A
3.3kV,150A
(100 mm2)2.5kV,100A
1.2kV,200A
(64 mm2)
600V,10A
(4 mm2)
1.2kV,70A
600V,100A
(36 mm2)
Co
nv
ersi
on
Cap
aci
ty (
kV
A)
(Volt
age
x C
urr
ent)
Year
Dev
ice
kil
ler
def
ect
den
sity
(cm
-2)
Beijing University SeminarBeijing, China, 2007.11.22 National Institute of Advanced Industrial Science and Technology
Summary
High-power electron devices are key components forwireless communication and power electronics, whichare necessary for the sustainable development in the21th century.
WGS are promising for high-power application, due totheir superior material characteristics.
Owing to the recent R&D, high-power electron deviceperformance by WGS has been well demonstrated,which much surpass those of conventional devices
There still remain technical issues to be solved, foractual system application.