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Complete suppression
of reverse annealing in neutron irradiated
MCZ Si detectors during gamma irradiation
Z. Li, W. Chen, R. Gul, J. Kierstead
Brookhaven National laboratory, USA
E. Verbitskaya, V. Eremin
Ioffe Physical-Technical Institute of Russian Academy of Sciences
St. Petersburg, Russia
J. Härkönen
Helsinki Institute of Physics, Finland
M. Hoeferkamp, J. Metcalfe, S. Seidel
University of New Mexico, Albuquerque, USA
18 RD50 Workshop
Liverpool, May 23-25, 2011
1
Outline
•
•
•
•
•
Background
Experimental
I-V characteristics
Current pulse response
Reverse annealing suppression by gamma
Conclusions
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
2
Background
Goal of the study
Develop radiation hard Si detector
that can utilize mixed irradiation in ILC:
gamma + electrons + neutrons
Task пѓћ compensation of donor-type and acceptor-type defects
The task of mixed irradiation is also important for LHC
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
3
Experimental
Samples:
p+-n-n+ Si detectors processed in BNL
n-type MCZ Si, r ~ 1 k, d = 390 Вµm
Characterization (all done at BNL):
пѓљ I-V, C-V
пѓљ TCT with red laser
пѓљ I-DLTS with infrared laser filling
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
4
Irradiation and annealing
Neutrons: Research Reactor in Sandia National Lab, 0.8-1 MeV,
Hardness Factor is 1.3),
Fn up to 3x1014 neq/cm2
Gamma: BNL’s 60Co Radiation facility (1.25 MeV),
to a total dose of 500 Mrad
n
RTA + g on two det.
1
RTA
2
3
22 days
12 month
5.5 month
Sample #
1480-13 1480-5
1st irradiation,
neq/cm2
1.5x1014 1.5x1014 3x1014
2nd irradiation, 0
gamma (Mrad)
500
time
1480-14 1480-16
0
3x1014
500
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
5
I-V characteristics: influence of gamma
RTA only
Gamma during 5.5 month
10-3
22 days
5.5 m
12 m
10-4
10-5
10-6
1
10
22 days
5.5 m
12 m
1480-13
current (A)
current (A)
10-3
100
bias voltage (V)
10-4
1480-5
10-5
10-6
1
10
100
bias voltage (V)
#1480-5: I-V did not change during gamma irradiation
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
6
Current pulse response
1480-13, 1.5x1014 n/cm2 (22 d RT anneal), MCZ n-type Si, p+/n/n+ structure
1480-13, 1.5x1014
Laser front, electron current from p+ to n+
Double junction, and SCSI seen
Neutrons only
14 cm-2
Fn-type
1.5x10
n/cm ,#
(221480-13,
d RT anneal) MCZ
p /n/n structure
n = Si,
2
+
+
Laser back, hole current from n+ to p+
RTA 22 days (1st interval, end)
electrons
Vfd = 187 V
p+
-SC (SCSI)/DJ n
n+
+
p+
holes
384 V
237 V
187 V
286 V
237 V
187 V
140 V
1480-13, 1.5x1014 n/cm2 (5.5 month RT anneal), MCZ n-type Si, p+/n/n+ structure
90 V
Laser front, electron current from p+ to n+
Double junction, and SCSI seen
Vfd from C-V
a) Electron transient p+
hпЃ® E1
90 V
RTA, 5.5 m
Electron transient
After RT
reverse anneal
140 V
h
e
+
n
(2nd
E2
b) Hole transient
int., end)
hпЃ®
Eb
412 V
354 V
315 V
286 V
168 V
W1 W
b
Vfd
W2
c) E-field proile
Z. Li, et al., 18 RD50 Workshop,
Liverpool, May 23-25, 2011
7
Current pulse response: impact of gamma
#1480-5, 1.5x1014 n/cm2 + 500 Mrad (lower Fn)
1480-5, 1.5x1014 n/cm2 (22 d RT anneal), MCZ n-type Si, p+/n/n+ structure
(1st
JustLaser
after
neutrons
int.,
end)
front, electron
current from p to
n
+
+
Double junction, and SCSI seen
1480-5, 1.5x1014 n/cm2 +500 Mrad gamma (5.5 month RT anneal),
MCZ n-type Si, p+/n/n+ structure
nd
Laser front, electron current from p+ to n+
Double junction, and SCSI seen
5.5 m RTA + gamma: 2 int., end
Before gamma and RT
reverse anneal
177 V
After gamma and RT
reverse anneal
167 V
158 V
160 V
140 V
130 V
138 V
91 V
Vfd from C-V Vfd(CV)
148 V
Pulse shapes and Vfd are similar
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
8
Current pulse response: impact of gamma
1480-16, 3x1014 n/cm2 (22d RT anneal), MCZ n-type Si, p+/n/n+ structure
14
2
1480-16, 3x10 n/cm +500 Mrad gamma (5.5 month RT anneal),
#1480-16, 3x1014 cm-2 +
500
(higher Fn)
MCZ
n-typeMrad
Si, p /n/n structure
Laser front, electron current from p+ to n+
Double junction, and SCSI seen
+
+
Laser front, electron current from p+ to n+
Double junction, and SCSI seen
RTA 5.5 m
After gamma and RT
reverse anneal
Before gamma and RT
reverse anneal
645 V
600 V
554 V
645 V
600 V
554 V
508 V
508 V
460 V
460 V
Vfd
Vfd
Pulse shapes and Vfd are also similar
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
9
Current pulse response: 12 month RTA
3rd interval, end, RTA 12 months
Lower Fn
0.06
0.015
1480-5
431
568
640
675
742
0.01
0.005
V
V
V
V
V
signal (V)
s ig nal (V)
1480-13
0
307 V
365 V
402 V
460 V
618 V
0.04
0.02
0
-10
0
10
20
30
40
50
60
70
80
-10
0
10
20
30
40
time (ns)
time (ns )
Q normaliz ed (arb. units )
1.2
1480-13; 1.4e14
n/cm2
1480-5; 1.5e14
n/cm2 + 500 Mrd
1
0.8
DP pulse shape arises at lower V
in detector irradiated by gamma
and is more pronounced
0.6
0.4
0.2
0
0
200
400
600
800
1000
bias v oltag e (V)
10
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
Evolution of Vfd and Neff vs. RTA
1200
0.0E+00
1480-13
1480-5
1480-14
1480-16
Vfd (V)
800
600
gamma
400
200
0
0
-2.0E+12
Neff (cm-3)
1000
Reverse anneal
resumes wih similar
rate
Reverse anneal
2
4
6
8
suppression RTA time (months)
Fn
(neq/cm2)
g-dose after neutron
-4.0E+12
-6.0E+12
1480-13
1480-5
1480-14
1480-16
-8.0E+12
-1.0E+13
10
12
14
0
2
4
6
8
10
12
RTA time (month)
irradiation during
5.5 m RTA (Mrad)
Changes in Neff
during 5.5 m
RTA
(cm-3)
Reverse
annealing
suppression
+SC would have
been generated
with gammaradiation alone
1.5x1014
500
+0.1x1012
completely
+1.5x1012
3x1014
500
~0
completely
+1.5x1012
1.5x1014
0
-1.8x1012
no
3x1014
0
-4.7x1012
no
Reverse anneal
resumes even in
gamma-irradiated
detectors when
gamma irrd. stops
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
11
14
I-DLTS spectra
1480-13, only neutrons
100 K: A-center
200-300 K:
V-- + cluster defects
RTA 5.5 months
5.5 m RTA: 1480-13
1480-5
1480-5, neutrons + gamma
P100/P300 = 0.36
P100/P300 = 0.87
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
12
Conclusions
In mixed irradiation neutrons + gamma:
•
Complete suppression of reverse annealing occurs only
during gamma irradiation, and disappears when gamma
stops, and reverse anneal resumes with similar rate
2. Suppression is independent on applied Fn
3. Interaction of different defects?
4. DP/DJ effects are observed also for mixed irradiation
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
13
Acknowledgments
This work was made in the framework of RD50 collaboration
and supported in part by:
• U.S. Department of Energy, Contract No. DE-AC02 -98CH10886,
• Fundamental Program of Russian Academy of Sciences
on collaboration with CERN,
• RF President Grant # SS-3306.2010.2
Thank you for attention!
Z. Li et al., 18 RD50 Workshop, Liverpool, May 23-25, 2011
14
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