veljko grilj ru đ er bošković institute, zagreb, croatia silicon detector workshop split,...
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DETECTOR TESTING FACILITY AT RBI(IBIC (Ion Beam Induced Charge) EXPERIMENT)
Veljko Grilj
Ruđer Bošković Institute, Zagreb, Croatia
Silicon Detector WorkshopSplit, Croatia, 8-10 October 2012
1. ACCELERATORS 1.0 MV HVE
Tandetron accelerator
6.0 MV EN Tandem Van de Graaff accelerator
IAEA beam line
TOF ERDA
PIXE/RBS
Dual-beam
irradiation
Ion microprobe
Nuclear reactions
In-air PIXE
PIXE crystal spectromet
er
Det.test
.IBIC
12
1.1. New detector testing beam line
1. Beam deflector and/or scanner
2. Pre-chamber with beam degrader/diffuser
3. Final chamber with beam in air capability
1.2. Nuclear microprobe
XY
protonbeam
scangenerator
XY
quadrupole doubletfocusing lens
sampleobject slits
IBIC signal
IBIC - chargecollection efficiency
images
IONS- p, , Li, C, O,..
RANGE - 2 to 200 m
ION RATE- currents 0 - 106 p/s
ION POSITION- focusing and scanning
500 10001E-6
1E-5
1E-4
1E-3
0,01
0,1
1
10
100
1000
10000
100000
Num
ber of
cha
rge
pairs
(io
n*nm
)-1
Depth (nm)
protons
CSi
Cu I
Eions = 1 MeV/amuMIPs
Silicon I 127 Si 28 C 12 He 4 H 1
Range(µm)E=1 MeV
0.37 1.13 1.6 3.5 16.3
Range (µm)E=10 MeV
3.7 4.8 9.5 69.7 709
proton
He12C
28Si127I
1.3. Available ion beams
Accel. voltages 0.1 to 6.0 MVNegative Ion sources:- Duoplasmatron- RF He- Sputtering
2. ION BEAM INDUCED CHARGE - theory
V
Q
V
Vout
Ouput signal Vout
Deposited energy
Principles of radiation detection techniques
Vout = F (deposited energy, free carrier transport)
Nuclear spectroscopy Well known
Free charge genetration and
transport
2. ION BEAM INDUCED CHARGE - theory
V
Q
V
Vout
Ouput signal Vout
Deposited energy
Principles of IBIC
Vout = F (deposited energy, free carrier transport)
Free charge genetration and
transport
Well known Material characterization
2. ION BEAM INDUCED CHARGE - theory
2
2
2
220
20
24
1ln2
ln4
c
v
c
v
I
vmNZ
vm
ze
dx
dE
Bethe formula:
a) Energy deposition by ions
Principles of IBIC
b) Creation of e-h pairs
6/ 10
eV
MeVEN
eh
dephe
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=0
vd
vq)t(I
year 1964
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
V
Q
V
Vout
d
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
T=1
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=2
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=3
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
V
Q
V
Vout
d
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
T=4
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=5
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=6
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=7
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=8
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=9
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=10
d
vq)t(I
2. ION BEAM INDUCED CHARGE - theory
c) Free charge carrier transport → charge induced at electodes
Principles of IBIC
.
))((
constVii
jV
trEvqi
Gunn’s theorem:
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
V
Q
V
Vout
d
T=11
2. ION BEAM INDUCED CHARGE - theory
Impact of defects on charge carriers mobility:
Principles of IBIC
-2 0 2 4 6 8 10 12 14 16
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
-2 0 2 4 6 8 10 12 14
0.000
0.025
0.050
0.075
0.0
0.2
0.4
0.6
0.8
1.0
I
Time
Q
d
vqI
qQtot
qQtot
t
d
vqI exp
created
induced
Q
QCCE - physical opservable:
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
startifinali
induced VVqQ
- direct implication from Gunn’s theorem:
.
))((
constVii
jV
trEvqi
- consequences:
electronsholes
ion beam
CCE 100%
a)
b)
- V0 - V0
-V 0
he
2. ION BEAM INDUCED CHARGE - theory
Advantages of using focused ions:- spatial resolution- wide spread of ion ranges
Principles of IBIC
20
mm
20 mm
Electrons10 keV
Electrons40 keV2 MeV H+ in Si 3 MeV H+ in Si
4 MeV H+ in Si
2 mm
4 mm
6 mm
47 m
m
90 m
m 147
mm
2. ION BEAM INDUCED CHARGE
PIN diode
Samples
2. ION BEAM INDUCED CHARGE
CVDdiamond
CdInGaSesolar cell
Si DSSD(16x16 strips)
Ion beam
Samples
Laura Grassi, W
ednesday,
16:00h
2. ION BEAM INDUCED CHARGE
100 m
Geometries
3. IBIC EXAMPLES
- by proper selection of ion type and energy, CCE (charge collection efficiency) at different sample depths can be imaged.
4.5 MeV Lirange 6μm
3 MeV protonsrange 90 μm
Si Schotky diode
proton
He12C
28Si127I
surface
bulk
Frontal IBIC
3. IBIC EXAMPLES
4.5 MeV Li7 ions (range in Si 8.5 m)
7.875 O16 ions(range in Si 4.5 m)
8.25.4
0
5.4
0
m
ionsLi
m
ionsO
dxdxdE
dxdxdE
Li image - O image / 2.8IBIC between 4.5 and 8.5 m
Frontal IBIC – depth profiling
Si Schotky diode
3. IBIC EXAMPLES
Frontal IBIC – drift & diffusion
d
W p
W
neutraldepletion dxL
Wx
dx
dEdx
dx
dEQQQ exp
0
drift diffusion
E ≠ 0
E = 0
minority carrier diffusion length
4H-SiC diode
3. IBIC EXAMPLES
d
W p
W
neutraldepletion dxL
Wx
dx
dEdx
dx
dEQQQ exp
0
drift diffusion
E ≠ 0
E = 0
Frontal IBIC – drift & diffusion
4H-SiC diode
3. IBIC EXAMPLES
d
W p
W
neutraldepletion dxL
Wx
dx
dEdx
dx
dEQQQ exp
0
drift diffusion
E ≠ 0
E = 0
Frontal IBIC – drift & diffusion
4H-SiC diode
3. IBIC EXAMPLES
d
W p
W
neutraldepletion dxL
Wx
dx
dEdx
dx
dEQQQ exp
0
drift diffusion
E ≠ 0
- direct measurement of diffusion length
Lp = (9.0±0.3) μm
Frontal IBIC – drift & diffusion
4H-SiC diode
3. IBIC EXAMPLES
Frontal IBIC – μτ mapping
E
d
d
ECCE
eh
eh
/
/ exp1
- from Gunn’s theorem with assumptions of full depletion, constant electric field and generation near one electrode:
Vcmave /101 23,
Vcmavh /104 25,
electrons holes
Hecht equation
CdZnTe- sample thickness > 2 mm
- IBIC with 2 MeV p+, range < 30 μm
M. Veale et al., IEEE TNS, 2008
Si power diode
E = 0
pn junction
E < 0
ion beam
0 zdz
CCE (z<zd) ≈ 1
CCE (z>zd) = exp(-(z-zd)/Lp,n)
hole or electrondiffusion length
3. IBIC EXAMPLES
Lateral IBIC – drift and diffusion
3 MeV proton beam
X-Y scanning
Cooling-heating
Bias Preamplifier Amplifier
ADC
Digital oscilloscope
DSO
TRIBIC
DAQ
IBIC MAPS
CdZnTe
Au-contacts
3. IBIC EXAMPLES
Temperature dependent lateral IBIC
CdZnTe
- temperature range 166-329 K
(mt)e=(1.4)*10-3 cm2/V(mt)h=1*10-5 cm2/V
(mt)e=(1.4)*10-3 cm2/V(mt)h=1*10-5 cm2/V
IBIC line scan (anode to cathode)for CCE=100%
3. IBIC EXAMPLES
Temperature dependent lateral IBIC
CdZnTe
3. IBIC EXAMPLES
Radiation hardness tests
- For 100% ion impact detection efficiency, IBIC
can be used to monitor irradiation fluence
- Irradiation of arbitrary shapes
- On-line monitoring of CCE degradation
Ion beam induced damage:
50 Li7 m-2 = 5×109 cm-2
6 Li7 m-2 = 6×108 cm-2
(4 events per pixel)
IBIC on-line monitoring:
Irradiation pattern (3 x3 quadrants, 50 x 50 pixels, 100 x 100 m2 each, 20 m gaps, tirrad = 5 min. – 3 h )
3. IBIC EXAMPLES
Radiation hardness tests
- damage done with He, Li, O & Cl ions of similar range
Si diode
3. IBIC EXAMPLES
Radiation hardness tests Modeling of CCE:- doping profiles & el. field (CV)- drift velocity profiles (el. field)- hole contribution negligible- vacancy profile (SRIM)- predominantly divacancies (DLTS)- dE/dx from (SRIM)- electron lifetime:
k = 0.88 *10-15
k = 0.18 !!18% of radiation induced defects leads to stable
divacancies !
heheKCCE ,*
,*1
hehek ,, effective fluence
Si diode
4. ION INDUCED DLTS
Question: how to calculate the energy levels of produced traps?
Answer: DLTS, but what if.....a) number of traps is very very large? b) I want good spatial resolution? c) my sample is diamod?
Radiation produces lattice defects el. active traps, CCE<100%
4. ION INDUCED DLTS
Question: how to calculate the energy levels of produced traps?
Answer: DLTS, but what if.....a) number of traps is very very large? b) I want good spatial resolution? c) my sample is diamod?
Ion Induced
DLTSSteps:- IBIC with MeV ions, charge carriers will fill traps - record cumulative collected charge in time using charge sensitive preamp and digital scope at different temperatures- choose rate windows like in conventional DLTS- plot Q(t2)-Q(t1) vs. T
- make Arrhenius analysis and get activation energy of the defect
Radiation produces lattice defects el. active traps, CCE<100%
4. ION INDUCED DLTS 6H-SiC diode
- irradiation with 1 MeV electrons, 215101 cm el. active traps, CCE<100%
- IBIC with 5.486 MeV alphas
cumulative collected charge 250K<T<320 K
Q(t2)-Q(t1) vs. T
Estimated activation energy:IIDLTS DLTS
0.50±0.05 eV 0.53±0.07 eV
N. Iwamoto et al., IEEE TNS, 2011
5. TIME RESOLVED IBIC - TRIBIC
C. Canali, E. Gatti, S.F. Koslov, P.F. Manfredi, C. Manfredotti, F. Nava, A. QuiriniNucl. Instr. Meth. 160 (1979) 73-77
t
d
vqI exp
ns15
(transient current technique, TCT)- use of current sensitive amplifier instead of charge
sensitive- high frequency oscilloscope, - novel technique ???
400 μm thick natural diamond
5. TIME RESOLVED IBIC - TRIBIC
- 2 GHz, 40 dB, 200ps rise time amplifier (CIVIDEC)- broad-band 3GHz scope (LeCroy)
TCT on scCVD diamond at low temperatures
H. Jansen (CERN), CARAT Workshop, GSI, 2011
Lower fields are required to reach saturation velocity at low tempertures
5. TIME RESOLVED IBIC - TRIBIC
Saturation velocity
H. Jansen (CERN), CARAT Workshop, GSI, 2011
Plasma effects
5. TIME RESOLVED IBIC - TRIBIC
Plasma effects
Significantely higher charge trapping at low temperatures !!
5. TIME RESOLVED IBIC - TRIBIC
Charge trapping/detrapping
H. Jansen (CERN), CARAT Workshop, GSI, 2011
Detrapping (~ 10 ns)
5. TIME RESOLVED IBIC - TRIBIC
Charge trapping/detrapping
H. Jansen (CERN), CARAT Workshop, GSI, 2011
5. TIME RESOLVED IBIC - TRIBIC
Position sensitivity- scCVD diamond, 500 μm thick- lateral scan with 4.5 MEV p- (μτ)e< (μτ)h
- 6 GHz, 15dB preamp (Minicircuits)- 5 GHz, 10 GS/s scope (LeCroy)
0 500μm
Achievable resolution ≈ 10 μm
500 μm thick scCVD diamond
Thank you for attention!