Download Eremin_RD50_Nov_2009 - Indico

CCE in irradiated silicon detectors
considering the avalanche effect
Vladimir Eremin,
by
Elena Verbitskaya, Andrei Zabrodskii
Ioffe institute St Petersburg, Russia
Zheng Li
BNL
Jaakko Haerconen
HIP
RD50 meeting, CERN, 16 – 18 Nov, 2009
Outline
•
•
•
•
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Model
The effect simulation
CCE(V) profile
CCE(F) profile
Summary
V.Eremin, RD50 Nov.2009
Experimental evidence of the gain
V.Eremin, RD50 Nov.2009
Electric field evolution with fluence in
PAD detectors (single peak model)
The electric field in PAD N on P silicon detector
1.8E+05
1.6E+05
Electric field, V/cm
d = 300um
V = 500V
g = 1.7e-2 cm-1
F=1e14
F=3e14
F=1E15
F=3E15
F=1E16
1.4E+05
1.2E+05
1.0E+05
8.0E+04
6.0E+04
4.0E+04
2.0E+04
0.0E+00
0.0E+00
5.0E-03
1.0E-02
1.5E-02
2.0E-02
2.5E-02
3.0E-02
Distance, cm
V.Eremin, RD50 Nov.2009
Depth profile of multiplication
probability
Avalanch probability along the detector
thickness
Avalanch probability, cm-1
3.5E+03
3.0E+03
Electrons, V=1000 V
2.5E+03
2.0E+03
1.5E+03
Holes, V=1000 V
Electrons, V=700 V
The N on P detector operates at:
RT
The detector thickness - 300um
Fluence 1e16 neq/cm2
Holes, V=700 V
1.0E+03
5.0E+02
0.0E+00
0.E+00
2.E-03
4.E-03
6.E-03
8.E-03
1.E-02
Distance, cm
Electric field in detector at different bias
voltage
2.5E+05
V=1000 V
Electric field, V/cm
2.0E+05
V=700 V
1.5E+05
g$531,1)
1.0E+05
5.0E+04
0.0E+00
0.E+00
2.E-03
4.E-03
6.E-03
Distance, cm
8.E-03
1.E-02
V.Eremin, RD50 Nov.2009
Voltage dependence of the CCE
The detector operates at RT.
The detector thickness is 300um.
Fluence 1e16neq/cm2
The trapping time: e= τp= 2.5e-10 s,
Electron collection to the n+ side
CCE(V)
5
4.5
CCE, arb.unt
4
3.5
3
2.5
2
1.5
1
0.5
0
0
200
400
600
800
1000
Voltage, V
Calculations are based on trivial SP detector model.
What is in a real strip detector ?
V.Eremin, RD50 Nov.2009
Current stabilization and electric field
smoothing around strip
The approach is based on explanation of the high breakdown voltage
for the heavily irradiated P on N silicon detectors via the electric
field suppression by the local current injection.
(V. Eremin et. al., “Scanning Transient Current Study of the I-V Stabilization Phenomenon in
Silicon Detectors Irradiated by Fast Neutrons”, NIM A, 388 (1977), 350.)
n+ strip
E(x)
Soft
breakdown
and
hole injection
accompanied
by trapping
X
V.Eremin, RD50 Nov.2009
Extractions
from the “Conclusions” of the talk
“The Avalanche Effect in Operation of Heavily Irradiated Si p-i-n Detectors”
V. Eremin (Friburg, 2009).
1. The charge multiplication in heavily irradiated detectors is based on
two fundamental mechanisms:
• the avalanche multiplication in P-N junctions
• the electric field manipulation by current injection in the deep level
dopped semiconductors.
2. The SPB model conceders a “strong feed-back loop” via the current
injection that explains the detector stable operation at the high voltage
and the smoothed rise of the collected charge up to 100% of CCE.
V.Eremin, RD50 Nov.2009
PTI model and origin of Double Peak (DP)
electric field distribution
V. Eremin, E. Verbitskaya, Z. Li. “The Origin of Double Peak Electric Field Distribution
in Heavily Irradiated Silicon Detectors”, NIM A 476 (2002) 556.
-V
Neff
trapping
Trapping of free carriers
from detector reverse current
to midgap energy levels
of radiation induced defects
leads to DP E(x)
DLs responsible for DP E(x) are midgap DLs:
DD: Ev + 0.48 eV
DA: Ec – 0.52 eV
V.Eremin, RD50 Nov.2009
Electric field manipulation
in bulk of heavily irradiated detector
by hole injection
30
n
+
Neutron irradiation
25
14
Fn = 1.4*10 cm
-2
E, kV/cm
20
T = 140 K
V = 210 Volt
15
2
j, nA/cm :
0.1
1
5
10
15
20
p
+
10
5
0
0
50
100
150
200
250
x, m
E.Verbitskaya et al., “Optimization of electric field distribution by free carriers injection ….”
IEEE trans., NS-49 (2002), p. 258.
V.Eremin, RD50 Nov.2009
PTI model of electric field stabilization
effect via the
“Soft Avalanche Break Down”
Multiplication probability
12000
10000
8000
6000
4000
2000
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Distance from p+ contact, cm
P+
N+
V.Eremin, RD50 Nov.2009
Calculation of the Electric field with
PTI model of “Soft Avalanche Break
Down”
DL #
D/A, 0/1
Ci-Oi
Deep donor
V-V
Deep acceptor
0
0
1
1
electrons
holes
electrons
holes
electrons
holes
electrons
holes
Et=Edl-Ev
0.36
0.76
0.48
0.64
0.7
0.42
0.595
0.525
sig/e[cm2] 1.00E-15
1.00E-15
1.00E-15
1.00E-15
sig/h[cm2]
1.00E-15
1.00E-15
1.00E-15
1.00E-15
Ndl[cm-3] 0.00E+00
2.00E+14
0.00E+00
5.00E+15
Sig*Vth
1.93E-08 1.47E-08 1.93E-08 1.47E-08 1.93E-08 1.47E-08 1.93E-08 1.47E-08
detrap.prob. 8.31E-04 1.42E+04 1.76E-01 6.73E+01 3.23E+03 3.66E-03 2.98E+01 3.97E-01
Fn = 1e16 cm-2, V = 1500, 1000, 700, 500V
350000
2.50E+06
300000
No SABD
Electric field, V/cm
Electric field, V/cm
2.00E+06
1.50E+06
1.00E+06
5.00E+05
0.00E+00
0.02
With SABD
250000
200000
150000
100000
50000
0
0.022
0.024
0.026
0.028
Distance from P+ contact, cm
0.03
0
0.005
0.01
0.015
0.02
0.025
0.03
Distance from P+ contact, cm
V.Eremin, RD50 Nov.2009
Voltage dependence of the multiplication
effect in detectors
Fn = 1e16 cm-2
CCE(V)
4000
Collected charge, pairs
5
4.5
CCE, arb.unt
4
No SABD
3.5
3
2.5
2
1.5
1
3500
3000
2000
1500
1000
500
0.5
0
0
200
400
600
800
0
1000
500
Voltage, V
700
900
1100
1300
1500
1300
1500
Voltage, V
5000
Collected charge, pairs
1200
Collected charge, pairs
X=0.029cm
2500
1000
X=0.0295 cm
800
600
400
200
4500
4000
3500
X=0.028 cm
3000
2500
2000
1500
1000
500
0
0
500
700
900
1100
Voltage, V
1300
1500
500
700
900
1100
Voltage, V
V.Eremin, RD50 Nov.2009
Fluence dependence of the multiplication
effect in detector
V = 1000V
X = 0.028cm
P+
N+
CCD ~ Vdr*ttr = 10e7*2.5e-10=25um
Q gen = 1000 e (10um of MIP track)
CCE mip = 30/300*10=1
Collected charge, pairs
2000
X
1800
1600
1400
1200
1000
800
600
400
200
0
1E+13
1E+14
1E+15
1E+16
Fluence, n/cm-2
V.Eremin, RD50 Nov.2009
Future
• The set of strip detectors with different width of
strips will be finished in 2009.
• Irradiation - spring 2010.
• CCE calculation for MIPs with PTI SABD model
V.Eremin, RD50 Nov.2009
Summary
• Earlier predicted phenomenon of stabilization of
the maximal electric field at n+ side of heavily
irradiated detectors is proofed.
• The soft CCE(V) characteristics of heavily
irradiated detectors were successfully modeled.
• The PTI DP model with effective 2 midgap levels
for E(X) distribution in irradiated detectors has
got new confirmation.
V.Eremin, RD50 Nov.2009