solid state physics group experimental physics dept. university … · 2003. 11. 18. · cdte x-ray...
TRANSCRIPT
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 1
ProjectsProjects“Diamond for ionizing radiation detection”, RD42-CERN collaboration and INFN"Research of charge transport properties in SiC by nuclear microprobe technique" project supported by NATO Science Programme“Silicon Carbide Radiation Detectors for Room and High Temperature Spectrometry”, COFIN-MIUR
• G.Bertuccio: Dept Elect Engn & Informat Sci, Politecnico of Milano• A.Cavallini: Physics Dept., University of Bologna• F.Nava: Physics Dept., University of Modena• C.Lanzieri:Alenia Marconi Systems, Roma (I)
Solid State Physics Group
Experimental Physics Dept. University of TorinoClaudio Manfredotti – Full professor
Ettore Vittone – Associated professor
Alessandro Lo Giudice – INFM researcher
Paolo Olivero – PhD student
Floriana Fasolo – PhD student
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 2
OUTLINEOUTLINE
• Introduction• Characterisation techniques:
– IBIC– IBIL– XBIC– XBIL
• Silicon Carbide characterisation• Radiation damage analysis• Neutron detection
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 3
IONISATION RADIATION micro-PROBES
Materials and devices
Si p-n junctions
CdTe x-ray detectors
GaAs Schottky diodes
Diamond radiation detectors
SiC Schottky diodes
Study of uniformity
Charge collection efficiency maps and profiles
Measurement of minority carrier diffusion length
Study of radiation induced damage
MeV ions keV x-raysIBIC - Charge collection efficiency - XBIC
IBIL - Radiation induced Luminescence - XBIL
Opto-electronic characterisation
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 4
Ion Beam AnalysisIon Beam AnalysisNuclear microprobe facility @
Ruđer Bošković Institute (Zagreb, Croatia)Dr. Milko Jaksic
•6 MV Tandem accelerator•available ions: H, C, Li, O, …•micrometric spot size•PIXE, IBICC measures
AN2000 microbeam facility @INFN National Laboratories (Legnaro ,I)
Dr. Valentino Rigato
2.5 MV Van de Graaff accelerator•available ions: H, He•micrometric spot size•PIXE, IBICC and IBIL measures•recently developed cryogenic apparatus
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 5
IBIC Set upIBIC Set up
frontal
lateral
Ion beam
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 6
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
19.34 -- 20.84 17.84 -- 19.34 16.34 -- 17.84 14.84 -- 16.34 13.34 -- 14.84 11.84 -- 13.34 10.34 -- 11.84 8.840 -- 10.34 7.340 -- 8.840 5.840 -- 7.340
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
87.10 -- 88.60 85.60 -- 87.10 84.10 -- 85.60 82.60 -- 84.10 81.10 -- 82.60 79.60 -- 81.10 78.10 -- 79.60 76.60 -- 78.10 75.10 -- 76.60 73.60 -- 75.10
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
96.80 -- 98.30 95.30 -- 96.80 93.80 -- 95.30 92.30 -- 93.80 90.80 -- 92.30 89.30 -- 90.80 87.80 -- 89.30 86.30 -- 87.80 84.80 -- 86.30 83.30 -- 84.80
75 80 85 90 95 100 1050
500
1000
1500FRB L12, frontale230 V
Pixe
l
Efficiency (%)
65 70 75 80 85 90 950
1000
2000
FRB L12, frontale93 V
Pix
el
Efficiency (%)
0 5 10 15 20 25 300
500
1000
1500
2000 FRB L12, frontale30 V
Pixe
l
Efficiency (%)
FRBBL12
C = 3x1014 cm-3
2 mm
1 cm
pre-amplifierSchottky contact
ohmic contact
(frontal irradiation)2 MeV protonmicrobeam
0.1
mm GaAs
(back irradiation)2 MeV protonmicrobeam
sample holder
active region
lateral IBIC2.4 MeV proton
microbeam
2 mm
1 cm
2 mm
1 cm
pre-amplifierSchottky contact
ohmic contact
(frontal irradiation)2 MeV protonmicrobeam
0.1
mm GaAs
(back irradiation)2 MeV protonmicrobeam
sample holder
active region
lateral IBIC2.4 MeV proton
microbeam
GaAs Schottky diodes
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 7
LATERAL IBICC; 2.4 MeV protons
40 60 80 100 120 140 160 180 200 220 240 2600,0
0,2
0,4
0,6
0,8
1,0
GaAs SL69-CT n.1LNL 14/16 Aprile 1998; Protoni 2.4 MeV
183 V 132 V 83 V
35 V
Effi
cien
za
Posizione (µm) 10 20 30 40 50 60 70 80 90100 20010
20
30
40
5060708090
100
200
GaAs SL69-CTLNL 14/16 Aprile 1998; Protons 2.4 MeV
Width = a*(bias)^bChi^2 = 0.7861a 1.15593 ±0.32994b 0.95314 ±0.05655
Dep
letio
n la
yer w
idth
(µm
)
Bias Voltage (V)
0 24 49 73 98 122 146 171 195 2200
24
49
73
98
122
146
171
195
220
244
268
V=+83
0 24 49 73 98 122 146 171 195 2200
24
49
73
98
122
146
171
195
220V=+35
0 24 49 73 98 122 146 171 195 2200
24
49
73
98
122
146
171
195
220
SchottkyBarrier
SchottkyBarrier
V=+132
1.0006.00011.0016.0021.0026.0031.0036.0041.0046.0051.0056.0061.0066.0071.0076.00
0 24 49 73 98 122 146 171 195 2200
24
49
73
98
122
146
171
195
220
100 µm
efficiency %
V=+183
GaAs
active region
Schottky contact
GaAs2.4 MeV H+
Ohmic contact
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 8
HAMAMATSU R376 fused silica window
(160-850 nm).
1200 l/mm blazed at 500 nm, spectral range 300-900 nm
Cathodoluminescence (CL) and Ionoluminescence (IL) Mono CL2 system by Oxford Instruments (F=30 cm, aperture=F/4.2)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 9
High irradiation dose produce damage.
In diamond it is possible to observe an intensity decrease of band A and 615 nm peak.
Also there is a 510 nm H3 centre creation.
( ) ( )DDII ⋅⋅−⋅⋅=−⋅= −1570 1012.1exp1091.1exp σ
0 1x1015 2x1015 3x1015 4x1015 5x10150,0
2,0x106
4,0x106
6,0x106
8,0x106
1,0x107
1,2x107
1,4x107
1,6x107
1,8x107
433
nm p
eak
area
[a.u
.]
Dose [Protons/cm2]
Experimental
First order exponential decay fit of data
Band A decay in sample CM1
300 400 500 600 700101
102
103
104
105
106
Scan1 Scan2 Scan3 Scan4 Scan5 Scan6
Cou
nts
[a.u
.]
Wavelenght [nm]
Sample: CM1
300 400 500 600 700101
102
103
104
105
106
Scan1 Scan2 Scan3 Scan4 Scan5 Scan6
Cou
nts
[a.u
.]
Wavelenght [nm]
Sample: R117
Proton damage in Proton damage in diamonddiamond
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 10
• hνX-ray = 2.5 ÷ 8 keV• synchrotron source• submicrometric spot size• XBICC, XBIL measures
ID21 X-ray microscopy beamline @European Synchrotron Radiation Facility
(Grenoble, France)Dr. R.Barrett and R.Tucoulou
XX--ray analysisray analysis
X
Y Z
Sample
Vbias
Electrode
Keithley 617picoamperometer
OndulatorCrystal
monochromatorZone plate
objective lens
Aperture Raster X-Ypiezo scanner
8
V (0-2 V)
ν (0-100 kHz)
∫ signal(# counts)
APMT
V → νX-ray µbeam
V (0-2 V)
ν (0-100 kHz)
∫ signal(# counts)
APMT
V → νX-ray µbeam
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 11
XBICC on diamondXBICC on diamond
XBICC map on diamond: the circular electrode is clearly visible; the black spot is the contacting silver drop; note the polycrystals (invisible to optical microscope)
Zooms (90x100 µm2) : “electronic” crystals are clearly visible, with sizes depending from the applied voltage
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 12
Silicon carbideSilicon carbide
Silicon carbide samples:• n-doped 4H-SiC epitaxial layers on n+-doped SiC substrates by CREE• gold Schottky contacts + guard rings by Alenia Marconi• ohmic T-Pt-Au contacts by Alenia Marconi
Ohmic contact - Ti/Pt/Au
n+, 4H – SiC, 360 µm
substrate
n, 4H – SiC, 40 ± 2 µm epitaxial 4H-SiC
circular Schottky contactNi2Si φ = 1.5 mm
Si-face
C-face
sample section schematics
The Schottky contacts have been formed on the silicon surface of the epitaxial layer by deposition of a thin Au film, 100 nm thick. Ti/Pt/Au metallization system was used to realise the ohmic contacts on the whole carbon back surface.The metallizations were obtained by e-beam deposition in high vacuum (10-7 torr) and no heat treatment was performed after metallization.
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 13
Schottky PotentialVbi=(0.959±0.007) V
Constant Doping DensityNd=(4.52±0.03)·1014
atoms/cm3
Ideality Factorη=(1.153±0.003)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 14
SiC sample IKZ P2220
Ohmic contact - Ti/Pt/Au
n+, 4H – SiC, 360 µm
substrate
n, 4H – SiC, 40 ± 2 µmepitaxial 4H-SiC
circular Schottky contactNi2Si φ = 1.5 mm Si-
face
C-face
Epitaxial layer (Institut für Kristallzuchtung of Berlin): N doping (from 4.7x1013 to 7.7x1013cm-3), 40 µm thick
Substrate (CREE): n+ doping (>1018 cm-3), 360 µm
Schottky contact + guard ring (Alenia Marconi): Ni2Si; 356 nm thick
Ohmic contact(Alenia Marconi): Ti-Pt-Au
F.Nava et at., to be published in NIMB
4H-SiC epitaxial layers grown at the Institut für Kristallzüchtung (Berlin) on 4H-SiC substrates by CREE
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 15
0 50 100 150 200 250 300 350 400 45010-11
10-10
10-9C
UR
REN
T D
ENSI
TY (A
/cm
2 )
REVERSE BIAS (V)
0 10 20 30 40 500
5
10
15
20
25
30
35
40
Dep
letio
n re
gion
wid
th (µ
m)
Bias Voltage (V)
0 5 10 15 204
5
6
7
8
9 4H-SiC #G
N(X
)[x10-1
3cm
-3]
X [µm]
Schottky Barrier height : 1.84 eV
Ideality factor:1.05
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 16
X
Y Z
Sample
Vbias
Electrode
Keithley 617picoamperometer
OndulatorCrystal
monochromatorZone plate
objective lens
Aperture Raster X-Ypiezo scanner
ID21 scanning x-ray microscope (SXM)ESRF - Grenoble (F)
3 keV x-ray energy; about 10 photons/s;8
Spot size about 1 mµAttenuation length in SiC: 4 mAu contact (100 nm thick): attenuation 33%
µ
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 17
XBICC on silicon carbideXBICC on silicon carbideXBICC maps
circular electrode
silver drop
zoom region
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 18
XBICC on silicon carbideXBICC on silicon carbideXBICC maps
At 0 V bias voltage point defects (micropipes?) are clearly visible, which disappear at higher bias voltages.
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 19
3.0 3.2 3.4 3.6 3.80
50
100
150
Photocurrent (a.u.)
BIAS = 0 Vab_02
Pix
els
3.0 3.2 3.4 3.6 3.80
50
100
150 BIAS = 50 Vab_08
Pixe
ls
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.60.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6Bias = 50 V
PhotoCurrent
X Axis (mm)
Y Ax
is (m
m)
3.1503.1603.1703.1793.1893.1993.2093.2193.2283.2383.2483.2583.2683.2773.2873.2973.3073.3173.3263.3363.3463.3563.3663.3753.3853.3953.4053.4153.4253.4343.4443.4543.4643.4743.4833.4933.5033.5133.5233.5323.5423.5523.5623.5723.5813.5913.6013.6113.6213.6303.6403.650
A
C
D B
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.60.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
PhotoCurrent
Bias = 0 V
X Axis (mm)
Y Ax
is (m
m)
3.1503.1603.1703.1793.1893.1993.2093.2193.2283.2383.2483.2583.2683.2773.2873.2973.3073.3173.3263.3363.3463.3563.3663.3753.3853.3953.4053.4153.4253.4343.4443.4543.4643.4743.4833.4933.5033.5133.5233.5323.5423.5523.5623.5723.5813.5913.6013.6113.6213.6303.6403.650
D
CB
A
P2220; from IfK
XBIC, ESRF
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 20
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.60.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
PhotoCurrent
Bias = 0 V
X Axis (mm)
Y Ax
is (m
m)
3.1503.1603.1703.1793.1893.1993.2093.2193.2283.2383.2483.2583.2683.2773.2873.2973.3073.3173.3263.3363.3463.3563.3663.3753.3853.3953.4053.4153.4253.4343.4443.4543.4643.4743.4833.4933.5033.5133.5233.5323.5423.5523.5623.5723.5813.5913.6013.6113.6213.6303.6403.650
D
CB
A
0 5 10 15 20 25 300
100
200
300
400
Pixe
ls
Photocurrent (A.U.)
10 20 30 40 50 60 70 80 90 100
10
20
30
40
50
60
70
80
90
100
V = -50 V
X Axis (µm)
Y A
xis (µm
)
23.0023.6924.3825.0625.7526.4427.1327.8128.5029.1929.8830.5631.2531.9432.6333.3134.00
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 21
X-Y Scanning system
Quadrupole focussing lenses
Sample holder
Analysis chamber
Sample
Vbias
Charge sensitivepre-amplifier
Amplifier
Electrode
X
Z
XY
IonBeam
Nuclear Microprobe at the Laboratory forIon Beam Interactions
Rudjer Boskovic Institute , Zagreb (HR)
H, Li, C, O
Ion Beam Induced Charge Collection Microscopy
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 22
0 200 400 600 800 1000 1200 1400 1600 1800 20000
200
400
600
800
1000
1200
1400
Noise
Peak #2
Peak #1
Test signal (pulser)
coun
ts
channel
Peak #1 map Peak #2 map
Vbias = 75 V
4H-SiC IKZ sample1.5 MeV protons
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 23
0 5 10 15 20 25
25
50
75
100
0.7 MeV
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 24
0.9 MeV
0 5 10 15 20 25
25
50
75
100
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 25
1.1 MeV
0 5 10 15 20 25
25
50
75
100
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 26
1.3 MeV
0 5 10 15 20 25
25
50
75
100
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 27
1.5 MeV
0 5 10 15 20 25
25
50
75
100
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 28
0 5 10 15 20 25
25
50
75
100
1.7 MeV
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 29
0 5 10 15 20 25
25
50
75
100
1.7 MeV
radiation damage (surface)
contact scratches (surface)
defects ? (depth)0.7 MeV
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 30
[ ]
potential weightedV
E(r)
velocity; hole(r)v ion;concentrat h)r;t'p(r,equation continuity holes the for function sGreen' the is
holes from Induced Charge thetheorem, Gunn-Ramo-Schockleythe From
Vi
p0
=∂∂
==
∂∂⋅⋅−= ∫ ∫
Ω
ole
V)r(E)r(v)r;'t,r(prd'dtq)t(Q
Vip0
t
0in
The continuity equation involves linear operators
The charge induced from holes can be evaluated by solving a single, time dependent adjoint equation.
( )p
p*
p0ppGpDp
tp
τ−+∇⋅+⋅φ∇⋅µ+⋅∇+=
∂∂ +
+++ rrr
ipp
in
VEG
Qp
∂∂
⋅φ∇⋅µ=
=
+
+
E.Vittone, IBA2003 conf., to be published in NIMB
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 31
−=+
Lxexp)x(p
Considering
-a one dimensional problem limited to the neutral region
-an infinite device thickness
-constant transport parameters (µ,τ)
The Green’s function of the continuiity equation, i.e. the solution of the adjoint equation for t→∞ is
p+ is the total charge induced at the sensing electrode by a moving charge generated at a distance x from the border of the neutral region.
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 32
Collected Charge ∫ ∫
−−⋅
+
=
W d
W pBSiCBSiCtot dx
LWxexp
dxdEdx
dxdEQ
0
11εε
DRIFT
Drift+Diffusion Model
BRAGG CURVE
(SRIM 2000)
BdxdE
Approximations
• Abrupt Junction
• Infinite semiconductor
DIFFUSION
∫
−−⋅
d
)V(W pB
dxL
)V(WxexpdxdE∫
)(
0
VW
B
dxdxdE
5.48 MeV He++
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 33
βεε b
SiSiC ⋅=
0 1 2 3 4 8 12 16 200
100
200
300
400
500
600
700
800
Depletion Layer
Width @
150 V
Energy Loss of He++ ions in SiCElectrode: 100 nm, Au
1.0 MeV He++ 1.5 MeV He++ 2.0 MeV He++ 5.48 MeV He++
Ener
gy L
oss
(keV
/um
)
Depth (µm)
Sample RUN1D3 (CREE): εSiC=(7.8±0.1) eVfrom He++ measurements
Sample SiCP2220 (IfK): εSiC=(7.5±0.1) eV from He++ measurements
Sample SiCP2220 (IfK): εSiC=(7.7±0.1) eV from H+ measurements
100% CCE in the depletion regionPlasma EffectsElectrode absorption
Fixed voltageFixed voltage; ; Variable Ion EnergyVariable Ion Energy
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 34
Run1D5
1.5 MeV H+
100 150 200 250 300 3500
10
20
30
40
50
coun
ts
channel
V=250 V
V=150 VV=90 VV=50 VV=10 VV=0 V
FWHM
40 keV
FWHM about 40 keV
V=50 V
V=100 V V=250 V
Fixed energyFixed energy; ; Variable voltageVariable voltage
Run1D3241Am α source
E=5.48 MeV
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 35
IBICC on silicon carbideIBICC on silicon carbidedetermination of hole diffusion length
Lh ≈ 5.8 µm Lh ≈ 8.6 µm
“Run1D3” sample, 5.48 MeV He “Run1D5” sample, 1.5 MeV H
⇓ ⇓τh ≈ 113 ns τh ≈ 247 nsif µh ≈ 115 V cm-2 s-1
is assumed
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 36
0 5 10 15 20 25 30 35 400
10
20
30
40
50
60
70
80
90
100
a)
Lp = 10.5 µmCC
E (%
)
REVERSE BIAS (V)
CCE-exp.CCE-driftCCE-diffusionCCE-theory
0 5 10 15 20 25 30 35 400
10
20
30
40
50
60
70
80
90
100
b)
Lp = 4.85 µm
CC
E (%
)
REVERSE BIAS (V)
Best WorstSiC sample IKZ P2220
F. Nava*, G. WagnerÄ, C. Lanzieri<, P. Vanni*, E. Vittone¨. “Investigation of Ni/4H-SiCdiodes as radiation detectors with low doped n-type 4H-SiC epilayers”, NIM B (2003)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 37
0 50 100 1500 50 100 1500
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 1000
10
20
30
40
50
60
70
80
90
100
He++ 4.14 MeV
REVERSE BIAS (V)
experimental theoretical fit drift only diffusion only
CC
E (%
)
He++ 5.48 MeV
REVERSE BIAS (V)
He++ 2.00 MeV
REVERSE BIAS (V)
0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,110-15
10-14
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
a)
# fluence (p/cm2)
0 9.37x1013
Proton Irradiated 4H-SiC
CU
RR
ENT
(A)
FORWARD BIAS (V)
0 40 80 120 160 20010-13
10-12
10-11
10-10
10-9
10-8
b)
Proton Irradiated 4H-SiC
# fluence (p/cm2)
0 9.37x1013
CU
RR
ENT
(A)
REVERSE BIAS (V)
F.Nava, E.Vittone, P.Vanni, G.Verzellesi, P.G.Fuochi, C.Lanzieri, M.Glaser, “Radiation Tolerance of epitaxial Silicon Carbide detectors for electrons, protons and γ –rays”,NIM A 505 (2003), 645
24 GeV/c proton irradiation @ 26°C
at the CERN-Proton Synchrotron
Fluence = 1.43x1013 protons/cm2
-6 -5 -4 -3 -2 -1 0 1 20
1x1016
2x1016
3x1016
4x1016
5x1016
6x1016
7x1016
8x1016
9x1016
1x1017
x
0 9.37 1013
# fluence (p/cm2)
Proton irradiated 4H - SiC
(Cap
acita
nce/
Area
)-2 (F
/cm
2 )-2
BIAS (V)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 38
0 50 100 150 200 2500,0
0,2
0,4
0,6
0,8
1,0
0 50 100 150 200 2500,0
0,2
0,4
0,6
0,8
1,0
0 50 100 150 200 2500,0
0,2
0,4
0,6
0,8
1,0
0 50 100 150 200 2500,0
0,2
0,4
0,6
0,8
1,0
CC
E
Φ=1.03 eVcc=0.7 µm/V1/2
L=9.5 µm
Bias voltage (V)
CC
EΦ=1.13 eVcc=0.8 µm/V1/2
L=1 µm
20 Mrad
Bias voltage (V)
2 Mrad
CC
E
Φ=1.06 eVcc=0.8 µm/V1/2
L=2 µm
Bias voltage (V)
8.2 MeV electron 0 Mrad 2 Mrad 20 Mrad 40 Mrad
He++ 4.14 MeV
CC
E
Bias voltage (V)
8.2 8.2 MeV electrons MeV electrons at ISOFat ISOF--CNR lab. CNR lab.
F.Nava, E.Vittone, P.Vanni, G.Verzellesi, P.G.Fuochi, C.Lanzieri, M.Glaser, “Radiation Tolerance of epitaxial Silicon Carbide detectors for electrons, protons and γ –rays”,NIM A 505 (2003), 645
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 39
0 40 80 120 160 200 240 280 3200
20
40
60
80
100
120
# Dose (Mrad) 0 2 10 20 40
4.14 - MeV alpha
60Co Gamma Irradiated 4H-SiC,
CC
E (%
)
REVERSE BIAS (V)
60Co Gamma at ISOF-CNR
F.Nava, E.Vittone, P.Vanni, G.Verzellesi, P.G.Fuochi, C.Lanzieri, M.Glaser, “Radiation Tolerance of epitaxial Silicon Carbide detectors for electrons, protons and γ –rays”,NIM A 505 (2003), 645
0 50 100 150 200 250
20
40
60
80
100
20
40
60
80
100
20
40
60
80
100
0 Mrad
Lp = 9.9 µmτp = 329.0 ns
a)
CC
E (%
) C
CE
(%)
CC
E (%
)
REVERSE BIAS (V)
c)
40 Mrad
Lp = 1.6 µmτp = 8.4 ns
2 Mrad
Lp = 5.0 µmτp = 84.4 ns
b)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 40
Electrical spectroscopy Ion spectroscopy
Sample Neff
(cm3)Φ
(eV)
n Hole diffusion length
(µm)
Virgin 2.18E15 1.7 1.19 8.57
Proton irradiated
1014 p/cm2
1.43E15 1.72 1.18 1.0
Virgin 2.49E15 1.03 1.04 9.5
Electron irradiated
2 Mrad
2.69E15 1.06 1.04 2
Electron irradiated
20 Mrad
1.67E15 1.13 1.036 1
Virgin 2.49E15 1.03 1.034 9.9
Gamma irradiated
2 Mrad
2.28E15 1.03 1.033 5
Gamma irradiated
40 Mrad
2.21E15 1.03 1.034 1.6
F.Nava, E.Vittone, P.Vanni, G.Verzellesi, P.G.Fuochi, C.Lanzieri, M.Glaser, “Radiation Tolerance of epitaxial Silicon Carbide detectors for electrons, protons and γ –rays”,NIM A 505 (2003), 645
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 41
IBICC on silicon carbideIBICC on silicon carbideIBICC maps – 2.0 MeV H+ induced damage
Consecutive IBIC scans ⇒ Charge collection efficiency as a function of adsorbed dose.
damaged region
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 42
0ppDp
p =τ
−∆⋅+
+
Hole adjoint continuity equation in the neutral region
Boundary conditions: p+(x=W)=1; p+(x=d)=0
)x(VK)x(N where)x(NvNv
1 irrirr
thirro
thop Φ⋅⋅=
⋅⋅σ+⋅⋅σ=τ
Nirr(x)= trap density
K = trap/vacancy
V(x) = Vacancy density/ion (vacancy/ion/cm)
F = fluence (ions/cm2/s)
5 10 15 20 25 30 35 40 45 500
1
2
3
4
5
6
7
8
Depth (um)
Vaca
ncy/
Ion/
um
SRIM2000 simulation
Vacancy/ion profileTotal Target Vacancies = 24 /Ion
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 43
charge drift charge diffusion
0 5 10 15 20 25 30 35 40 45 500
50
100
150
dW0
Depl
etio
n la
yer
Ener
gy lo
ss (k
eV/µ
m)
Depth (µm)
∫ ∫ +⋅
ε+
ε=
W
0
d
W BSiCBSiCtot dx)x(p
dxdE1dx
dxdE1Q
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 44
Hole diffusion length profile Hole induced charge profile
K ⋅ σirr⋅vth=2.8x105 cm3/s
Assuming
σirr=10-13cm2 and vth=107cm/s
K=0.28 traps/vacancy
Since
About 24 vacancy/ion -> 6-7 traps/ion
0 10 20 30 40 500
1
2
3
4
5
6
7
8
9
Depth (um)
L (u
m)
0 10 20 30 40 5010-10
10-8
10-6
10-4
10-2
100
Depth (um)
p+ (u
m)
Φ=0
Φ=108 cm2 s-1
Φ=109 cm2 s-1
Φ=1010 cm2 s-1
Φ=4x1010 cm2 s-1
1 10 100100
110
120
130
140
150
160
170
Data: dann_DModel: user8 Chi^2/DoF = 0.61317R^2 = 0.99853 alfa 0.27968 ±0.00562coeffang 370.7071 ±1.30944termnot 22.96335 ±0.53554
Cha
nnel
Fluence (ions/cm2)
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 45
AmBe Neutron Source @ JRC IspraActivity: 3.6x107 neutrons/s
Fast neutron detection
circular Schottky contactAu (1000 Å), Φ = 2 mm
Si-face
C-face, Ohmic contact
Plexigas6LiF
4H-SiC
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 46
Fast neutron detection6Li Converter: Reaction 6Li(n,α)3H
Neutron cross section from LANL laboratory web site: http://t2.lanl.gov
Q-value of the (n,α) reaction: 4.78 MeV
Activity: 600 GBq
3.6·107 neutroni/s
No radiation damage was detected after an irradiation of about 109 neutron/cm2.
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 47
C cross sections
Elastic
12C(n,α)9Be
Si cross sections
28Si(n,α)25Mg
Elastic
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 48
Exposure @ the TAPIRO reactor at the ENEA Casaccia Center (Rome)
Giancarlo Rosi
10-2 10-1 100 101 102 1x103 104 1x105 106 1070
1x108
2x108
3x108
Neu
tron
flux
[cm
-2 s
-1]
En [eV]
The nominal power i 5 kW and the neutron flux is 4x1012 cm-2s-1 at the core center.
The irradiation was performed using an epithermal column.
Reactor power = 5 W or 10 W
Neutron flux: about 1-2x106 n cm-2s-1
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 49
Plexigas6LiF
IkZ_U3 4H-SiC
0 250 500 750 1000 1250 1500 1750 20000
2
4
6
8
10
12
14
16
Bias voltage = 2 V
Cou
nts
Energy [keV]
Reactor power = 10 WNeutron flux=2.3x106 n cm-2s-1
Acquisition = 900 sNeutron fluence = 2x109 n cm-2
3.6 cm thick moderator10-2 10-1 100 101 102 1x103 104 1x105 106 107
2x102
2x103
2x104
2x105
Torino, 11/10/03 MCNP4B simulationNeutron source: Tapiro reactor @ Power (10 W)Neutron flux behind LiF; Real geometry
without moderator with 3.6 cm polyethilene
Neu
tron
flux
[cm
-2 s
-1]
En [eV]
4He =2.05 MeV 3H =2.73 MeV0.2% counting efficiency
No counting and charge collection efficiency decrease after 3.7*1010 neutroni/cm2
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 50
CONCLUSIONSCONCLUSIONS
• Uniformity analysis IBIC-XBIC• “Definition of measurement scheme and
parameters necessary to extract for device modelling”
• Radiation damage• 4H-SiC Schottky diodes for neutron detection;
MCNP simulation
Ettore Vittone CERN, 3rd RD50 Workshop, 3-5.11.2003 51