C.Manfredotti, Quartu S.Elena, 27-30.5.2001 1 WOCSDICE 2001 GaAs IBIC analysis of gallium arsenide...
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C.Manfredotti, Quartu S.Elena, 27- 30.5.2001 1 WOCSDICE 2001 GaAs IBIC analysis of gallium arsenide IBIC analysis of gallium arsenide Schottky diodes Schottky diodes C.Manfredotti 1,2 , E.Vittone 1,2 ,F.Fizzotti 1,2 , A.LoGiudice 1,2 , F.Nava 3 1 Dip. Fisica Sperim., Università di Torino, INFN-Sez. di Torino, via P.Giuria 1, 10125 Torino (I) 2 INFM- Unità di Torino Università, via P.Giuria 1, 10125 Torino (I) 3 Dip. di Fisica, Universitá di Modena, Via Campi 213/A, 41100 Modena, Italy
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Transcript of C.Manfredotti, Quartu S.Elena, 27-30.5.2001 1 WOCSDICE 2001 GaAs IBIC analysis of gallium arsenide...
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
1WOCSDICE 2001GaAs
IBIC analysis of gallium arsenide Schottky diodesIBIC analysis of gallium arsenide Schottky diodes
C.Manfredotti1,2, E.Vittone1,2,F.Fizzotti1,2, A.LoGiudice1,2, F.Nava3
1Dip. Fisica Sperim., Università di Torino, INFN-Sez. di Torino, via P.Giuria 1, 10125 Torino (I)2INFM- Unità di Torino Università, via P.Giuria 1, 10125 Torino (I)3 Dip. di Fisica, Universitá di Modena, Via Campi 213/A, 41100 Modena, Italy
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
2WOCSDICE 2001GaAs
SummarySummary
IBIC ( ION BEAM INDUCED CHARGE ) PRESENTED AS A POWERFUL METHOD IN ORDER TO INVESTIGATE ELECTRICAL FIELD DEPTH PROFILE AND ELECTRICAL HOMOGENEITY OF DEVICES
FRONTAL IBICC : RESULTS ON ELECTRICAL HOMOGENEITY OF CARBON DOPED n- TYPE SAMPLES
LATERAL IBICC : ANALYSIS OF RESULTS OBTAINED FROM A STANDARD SI SAMPLE IN COMPARISON WITH THEORETICAL MODELS
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
3WOCSDICE 2001GaAs
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 IBIC
2.4 MeV protonmicrobeam
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
4WOCSDICE 2001GaAs
IBIC Set upIBIC Set up
frontal
lateral
Ion beam
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
5WOCSDICE 2001GaAs
FRONTAL IBIC
• 2 MeV protons ( range in SiC 34 m )
• microbeam diameter 2 m
• scan area up to 2 x 2 mm2
• event-by-event data collection mode
• “ historical “ check of possible effects of radiation damage
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
6WOCSDICE 2001GaAs
GaAs carbon doping effects ( Freiberger ):- lowering of dark current- compensation of EL2 traps ( ? )- lowering of charge collection efficiency
2 samples
L12 C conc. 3 1014 cm-3
A15 C conc. 8 1014 cm-3
Frontal IBICEffect of carbon doping on charge collection efficiency uniformity
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
7WOCSDICE 2001GaAs
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
1500
FRB L12, frontale230 V
Pix
el
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
Pix
el
Efficiency (%)FRBBL12
C = 3x1014 cm-3
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
8WOCSDICE 2001GaAs
FRBAn15
C = 8x1014 cm-3
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
82.40 -- 83.40 81.40 -- 82.40 80.40 -- 81.40 79.40 -- 80.40 78.40 -- 79.40 77.40 -- 78.40 76.40 -- 77.40 75.40 -- 76.40 74.40 -- 75.40 73.40 -- 74.40
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
88.00 -- 89.00 87.00 -- 88.00 86.00 -- 87.00 85.00 -- 86.00 84.00 -- 85.00 83.00 -- 84.00 82.00 -- 83.00 81.00 -- 82.00 80.00 -- 81.00 79.00 -- 80.00
0 20 40 60 80 100 1200
20
40
60
80
100
120
X Axis
Y A
xis
92.30 -- 93.30 91.30 -- 92.30 90.30 -- 91.30 89.30 -- 90.30 88.30 -- 89.30 87.30 -- 88.30 86.30 -- 87.30 85.30 -- 86.30 84.30 -- 85.30 83.30 -- 84.30
70 75 80 85 90 95 1000
1000
2000
FRB A N.15, frontale355 V
Pix
el
Efficiency (%)
70 75 80 85 90 95 1000
1000
2000
FRB A N.15, frontale215 V
Pix
el
Efficiency (%)
70 75 80 85 90 95 1000
1000
2000
FRB A N.15, frontale167 V
Pix
el
Efficiency (%)
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
9WOCSDICE 2001GaAs
0 50 100 150 200 250
20
40
60
80
100
0 100 200 300 400
20
40
60
80
100
FRBL12
C = 3x1014 cm-3FRBAn15
C = 8x1014 cm-3
Effi
cien
cy (
%)
Voltage (V)
median mean FWHM x 10
Voltage (V)
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
10WOCSDICE 2001GaAs
LATERAL IBIC
• 2 MeV protons
• polished cross section surfaces
• no surface effect : penetration depth 34 mm and 2/3 of energy released at the end of the range ( Bragg’s peak )
• the electric field keeps apart the generated carriers : no plasma recombination
• charge collection efficiency values ( cce ) are obtained by comparison with a Si surface barrier detector
• cce profiles may be obtained from different regions of the scanned area by averaging over different rows or columns
• by fitting data by using an equation for cce obtained on the basis of Ramo’s theorem ) it is possible to check with different possible electrical field profiles
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
11WOCSDICE 2001GaAs
LATERAL IBICC
2.4 MeV protons
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
1.000
6.000
11.00
16.00
21.00
26.00
31.00
36.00
41.00
46.00
51.00
56.00
61.00
66.00
71.00
76.00
0 24 49 73 98 122 146 171 195 2200
24
49
73
98
122
146
171
195
220
100 m
efficiency %
V=+183
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
12WOCSDICE 2001GaAs
0 20 40 60 80 100 120 140 160 180 200 220
10
20
30
40
50
60
70
0 20 40 60 80 100 120 140 160 180 200 220
10
20
30
40
50
60
70
0 20 40 60 80 100 120 140 160 180 200 220
10
20
30
40
50
60
70
0 20 40 60 80 100 120 140 160 180 200 220
10
20
30
40
50
60
70
V=+83
V=+35
V=+132
Sch
ottk
y B
arr
ier
V=+183
%
x (m)
2020 30 40 50 60 70 8090100100 20020
30
40
50
60708090
100
200
Slope 0.89De
ple
tion
wid
th (
m )
Bias voltage ( V )
IBICC collection efficiency profiles
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
13WOCSDICE 2001GaAs
e=1.4 ns
e=1.3 ns
W=65 m
e=1.5 ns
e=1.5 ns
W=65 m
e=1.3 ns
e=1.3 ns
W=45 m
e=1.8 ns
e=1.5 ns
W=47 m
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
14WOCSDICE 2001GaAs
CONCLUSIONS
Frontal IBIC: Compensation with C : increases the homogeneity of the response, worsens energy resolution,
but
lowers the charge collection efficiency.
C.Manfredotti, Quartu S.Elena, 27-30.5.2001
15WOCSDICE 2001GaAs
CONCLUSIONS
Lateral IBICResults are in perfect agreement with the model based on electrical
field activated compensation of donors by EL2 centers
The depletion layer width increases almost linearly with bias voltage.
Different kinds of approximation of electrical field profile give very similar results concerning electron and hole lifetimes, but different depletion layer widths.
It may not be appropriate to use Hecht’s relationship in order to interpret the results, because in the presence of space charge Ramo’s theorem is no more valid: the extended Ramo’s theorem or better Gunn’s principle are needed.
