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CCE in irradiated silicon detectors considering the avalanche effect. by Vladimir Eremin , Elena Verbitskaya, Andrei Zabrodskii Ioffe institute St Petersburg, Russia Zheng Li BNL Jaakko Haerconen HIP. RD50 meeting, CERN, 16 – 18 Nov, 2009. Outline. Model The effect simulation - PowerPoint PPT Presentation
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Vladimir Eremin, Elena Verbitskaya, Andrei ZabrodskiiIoffe institute St Petersburg, Russia
Zheng LiBNL
Jaakko HaerconenHIP
CCE in irradiated silicon detectors considering the avalanche effect
RD50 meeting, CERN, 16 – 18 Nov, 2009
Outline
• 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
0.0E+00
2.0E+04
4.0E+04
6.0E+04
8.0E+04
1.0E+05
1.2E+05
1.4E+05
1.6E+05
1.8E+05
0.0E+00 5.0E-03 1.0E-02 1.5E-02 2.0E-02 2.5E-02 3.0E-02
Distance, cm
Ele
ctr
ic f
ield
, V
/cm
F=1e14F=3e14F=1E15F=3E15F=1E16
d = 300umV = 500Vg = 1.7e-2 cm-1
V.Eremin, RD50 Nov.2009
Depth profile of multiplication probability
Avalanch probability along the detector thickness
0.0E+00
5.0E+02
1.0E+03
1.5E+03
2.0E+03
2.5E+03
3.0E+03
3.5E+03
0.E+00 2.E-03 4.E-03 6.E-03 8.E-03 1.E-02
Distance, cm
Av
ala
nc
h p
rob
ab
ilit
y,
cm
-1
Electrons, V=1000 V
Holes, V=1000 V
Electrons, V=700 V
Holes, V=700 V
Electric field in detector at different bias voltage
0.0E+00
5.0E+04
1.0E+05
1.5E+05
2.0E+05
2.5E+05
0.E+00 2.E-03 4.E-03 6.E-03 8.E-03 1.E-02
Distance, cm
Ele
ctr
ic f
ield
, V
/cm V=1000 V
V=700 V
g$531,1)
The N on P detector operates at:RT The detector thickness - 300umFluence 1e16 neq/cm2
V.Eremin, RD50 Nov.2009
Voltage dependence of the CCE
CCE(V)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000
Voltage, V
CC
E,
arb
.un
t
The detector operates at RT.The detector thickness is 300um.Fluence 1e16neq/cm2The trapping time: τe= τp= 2.5e-10 s, Electron collection to the n+ side
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
E(x)
X
Soft breakdownand hole injection accompanied by trapping
n+ 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.)
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.
trapping
-V
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
Neff
V.Eremin, RD50 Nov.2009
Electric field manipulation in bulk of heavily irradiated detector
by hole injection
0 50 100 150 200 2500
5
10
15
20
25
30
p+n
+
T = 140 KV = 210 Volt
Neutron irradiation
Fn = 1.4*1014
cm-2
j, nA/cm2:
0.1 1 5 10 15 20
E, kV
/cm
x, m
V.Eremin, RD50 Nov.2009
E.Verbitskaya et al., “Optimization of electric field distribution by free carriers injection ….” IEEE trans., NS-49 (2002), p. 258.
PTI model of electric field stabilization effect via the
“Soft Avalanche Break Down”
0
2000
4000
6000
8000
10000
12000
0 0.005 0.01 0.015 0.02 0.025 0.03
Distance from p+ contact, cm
Mu
ltip
lica
tio
n p
rob
abil
ity
P+ N+
V.Eremin, RD50 Nov.2009
Calculation of the Electric field with PTI model of “Soft Avalanche
Break Down”DL # Ci-Oi Deep donor V-V Deep acceptorD/A, 0/1 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 0.525sig/e[cm2] 1.00E-15 1.00E-15 1.00E-15 1.00E-15sig/h[cm2] 1.00E-15 1.00E-15 1.00E-15 1.00E-15Ndl[cm-3] 0.00E+00 2.00E+14 0.00E+00 5.00E+15Sig*Vth 1.93E-08 1.47E-08 1.93E-08 1.47E-08 1.93E-08 1.47E-08 1.93E-08 1.47E-08detrap.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
0
50000
100000
150000
200000
250000
300000
350000
0 0.005 0.01 0.015 0.02 0.025 0.03
Distance from P+ contact, cm
Ele
ctr
ic f
ield
, V
/cm
Fn = 1e16 cm-2, V = 1500, 1000, 700, 500V
0.00E+00
5.00E+05
1.00E+06
1.50E+06
2.00E+06
2.50E+06
0.02 0.022 0.024 0.026 0.028 0.03
Distance from P+ contact, cm
Ele
ctri
c fi
eld
, V/c
m
No SABD With SABD
V.Eremin, RD50 Nov.2009
Voltage dependence of the multiplication effect in detectors
0
200
400
600
800
1000
1200
500 700 900 1100 1300 1500
Voltage, V
Co
llec
ted
ch
arg
e, p
air
s
0
500
1000
1500
2000
2500
3000
3500
4000
500 700 900 1100 1300 1500
Voltage, V
Co
llec
ted
ch
arg
e, p
air
s
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
500 700 900 1100 1300 1500
Voltage, V
Co
llec
ted
ch
arg
e, p
air
s
X=0.028 cm
X=0.029cm
X=0.0295 cm
CCE(V)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000
Voltage, V
CC
E,
arb
.un
t No SABD
Fn = 1e16 cm-2
V.Eremin, RD50 Nov.2009
Fluence dependence of the multiplication effect in detector
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1E+13 1E+14 1E+15 1E+16
Fluence, n/cm-2C
olle
cted
ch
arg
e, p
airs
V = 1000VX = 0.028cm
P+ N+
CCD ~ Vdr*ttr = 10e7*2.5e-10=25umQ gen = 1000 e (10um of MIP track)CCE mip = 30/300*10=1
X
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