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Radiation Hardness of High Resistivity CZ Si Detectors ... · 99.7 V 846 V 767 V •TCT...
Transcript of Radiation Hardness of High Resistivity CZ Si Detectors ... · 99.7 V 846 V 767 V •TCT...
Radiation Hardness of High Resistivity CZ Si Detectors after Gamma, Neutron and
Proton RadiationsZ. Li1, J. Harkonen 2, W. Chen1, J. Kierstead1, P.
Luukka2, E.Tuominen2, E. Tuovinen2, E. Verbitskaya3, and V. Eremin3
1 Brookhaven National Laboratory, Upton, NY 11973-5000, USA2 Helsinki Institute of Physics, P.O. Box 64, University of Helsinki,
Helsinki, 00014, Finland3 Ioffe Physico-Technical Institute, Polytechnicheskaya Str. 26, St.
Pertersburg, 194021, Russia
This research was supported by the U.S. Department of Energy: contract No: DE-AC02-98ch10886
OUTLINE
• Introduction• Experimental
SamplesRadiation sourceMeasurements
• Results and discussions
• Summary
Introduction• Oxygenated (HTLT and DOFZ) Si detectors are more rad
hard to charged particles and gamma than STD FZ detectors
• [O] in oxygenated Si: in the 1017’s /cm3
• [O] in STD FZ Si: in the 1015’s /cm3
• [O] in CZ Si: in the 1018’s /cm3
Comes naturally from wafer manufacture process Resistivity ≤100 Ω-cmThermal donor (TD) a problem
• Magnetic CZ technology now available:High [O]High resistivity ≥1000 Ω-cm : almost detector grade
• Is MCZ Si detector more radiation hard than Oxy Si?Gamma radiation could offer a clear clueHow about to neutrons and protons?
Experimental• Samples
Control FZ (CFZ) samples and some MCZ samples processed together by Univ. of Helsinki, and some MCZ samples were processed by BNL Oxidation: 8+5 hours in O2 at 1050 ºC, all diodes are p+/n/n+ junctions
Various square diodes of 0.36 cm2 each from each wafer were used
• Radiation 60Co gamma: E = 1.25 MeV; Dose rate: 0.5 Mrad/hr; Dose range: 0-1.2
Grad Neutrons: <E>=1 MeV; fluence: 0 to 2.9x1014 n/cm2
Protons: 10 MeV and 20 MeV; fluence: 0 to 1.2x1014 p/cm2
• Measurements
C-V measurements at RT and 100 kHzTCT measurements using a red laser
Wafer # Type Resistivity (Ω-cm) Thickness (µm)T15, 1 CFZ 3000 520
O6, 3 MCZ 1200 380
10 V
497 V
120 V
•TCT measurements (CFZ) 867 Mrad:Laser on the p+ side (front side): - SC, Double peak/junction seen
•TCT measurements (CFZ) 867 Mrad:Laser on the n+ side (back side): - SC, Double peak/junction seen
10 V
497 V
120 V
10 V
394 V
208 V
•TCT measurements (CFZ) 1004 Mrad:Laser on the p+ side (front side): - SC, Double peak/junction seen
•TCT measurements (CFZ) 1004 Mrad:Laser on the n+ side (back side): - SC, Double peak/junction seen
10 V
394 V
208V
Gamma Radiation
197 V
499 V
248 V
•TCT measurements (CFZ) 1177 Mrad:Laser on the p+ side (front side): - SC, Double peak/junction seen
•TCT measurements (CFZ) 1177 Mrad:Laser on the n+ side (back side): - SC, Double peak/junction seen
199 V
499V
248V
For CFZ diodes after gamma radiation:
o SCSI clearly observed ----- negative space charge build-upo SCSI taking place between 600 to 700 Mrado DJ/DP clearly observed after SCSI
•TCT measurements (MCZ) 1004 Mrad:Laser on the p+ side (front side): + SC
99.7 V
846 V
767 V
•TCT measurements (MCZ) 1177 Mrad:Laser on the p+ side (front side): + SC
99.8 V
999 V
750 V
•TCT measurements (MCZ) 1004 Mrad:Laser on the n+ side (back side): + SC
99.9 V
848 V
768 V
•TCT measurements (MCZ) 1177 Mrad:Laser on the n+ side (back side): + SC
99.8 V
993 V
750 V
For MCZ diodes after gamma radiation:
o No SCSI observed up to 1.2 Grad ----- no net negative space charge build-upo Vfd increases with dose: net positive space charge build-upo No DJ/DP observed up to 1.2 Grad
197 V
499 V
248 V
•TCT measurements (CFZ) 1177 Mrad:Laser on the p+ side (front side): - SC, Double peak/junction seen
•TCT measurements (MCZ) 1177 Mrad:Laser on the p+ side (front side): + SC
99.8 V
999 V
750 V
•Comparison of CFZ and MCZ detectors after gamma radiation to 1177 Mrad:
Laser on the p+ side (front side), electron drift current
•TCT measurements (MCZ) 1177 Mrad:Laser on the n+ side (back side): + SC
99.8 V
993 V
750 V
•TCT measurements (CFZ) 1177 Mrad:Laser on the n+ side (back side): - SC, Double peak/junction seen
199 V
499V
248V
•Comparison of CFZ and MCZ detectors after gamma radiation to 1177 Mrad:
Laser on the n+ side (back side), hole drift current
0 200 400 600 800 10001200
Gamma Dose (Mrad)
-3-2-101234567
(E12
)
Nef
f (1/
cm3)
FZ (533 um)
CZ (375 um)
HTLTOxygenated S
CZ and FZ wafers
+SC
-SC
670 Mrad-1.82E9*Dose (in Mrad)
2.92E9*Dose (in Mrad)
OXY Si: 4.1E8*Dose (in Mrad)
Negative SC build-up for control FZ Si detectors is: -1.82x109 x DosePositive SC build-up for Oxy Si detectors is: 4.1 x108 DosePositive SC build-up for MCZ Si detectors is: 2.9 x109 x Dose, about 8 times higher
• TCT measurements (MCZ): 8.2x1013 n/cm2
Laser on the p+ side (front side): -SC and DJ/DP
6.8 V
288 V
115 V
• TCT measurements (MCZ):8.2x1013 n/cm2
Laser on the n+ side (back side): -SC
6.7 V
288 V
115 V
Neutron Radiation
• TCT measurements (MCZ): 2.9x1014 n/cm2
Laser on the p+ side (front side): -SC & DJ/DP
78 V
629 V
520V
• TCT measurements (MCZ): 2.9x1014 n/cm2
Laser on the n+ side (back side): -SC
78 V
630 V
520V
• For MCZ Si detectors, SCSI takes place between 3.3x1013
n/cm2 and 8.2x1013 n/cm2 after 1 MeV neutron radiation.
• Double junction and double peak (DJ/DP) have been observed after SCSI
• TCT measurements (CFZ): 8.2x1013 n/cm2
Laser on the p+ side (front side): -SC and DJ/DP
89 V
569 V
320V
• TCT measurements (CFZ): 8.2x1013 n/cm2
Laser on the n+ side (back side): -SC
89 V
383 V
320V
• TCT measurements (CFZ): 2.9x1014 n/cm2
Laser on the p+ side (front side): -SC (only front junction seen)
79 V
767V
320V
• TCT measurements (CFZ): 2.9x1014 n/cm2
Laser on the n+ side (back side): -SC (only one junction seen)
76 V
769 V
430 V
• TCT measurements (CFZ): 2.9x1014 n/cm2
Laser on the p+ side (front side): -SC and DJ/DP
760 V
846 V
797 V
0 10 20 30 40
Neutron Fluence (1E13 n/cm2)
0100200300400500600700800900
1000
Full
Dep
eltio
n V
olta
ge
CZ3-day RTA
CZ10-day RTA
FZ3-day RTA
FZ10-day RTA
CZ and FZ wafers
Full depletion voltage vs. n-fluence
0 10 20 30 40 50
1 MeV equivalent n- Fluence (1E13 n/cm2)
-7-6-5-4-3-2-101234
(E12
)
Nef
f (1/
cm3)
CZ(b=0.017)n-rad
FZ(b=0.022)n-rad
CZ(b=0.0045)p-rad
CZ and FZ wafers
+SC
-SC
Space charge sign inversion (SCSI)
Neff vs. n-fluence
• TCT measurements (MCZ):1.7x1013 n/cm2
Laser on the n+ side (back side): +SC
9.4 V
491 V
277 V
491.8V
337.8V
277.9V
197.9V
148.2V
Reverse Anneal (9 month RTA)
Full depletion
+SC
+SC RT Reverse Anneal in 9 month: -99 volts or-SC increasing rate: 0.050 /n-cm
• TCT measurements (CFZ): 1.7x1013 n/cm2
Laser on the p+ side (front side): +SC
8.8 V
297 V
160V
• TCT measurements (CFZ): 1.7x1013 n/cm2
Laser on the n+ side (back side): +SC
8.8 V
297 V
160V
SCSI
296.8V
157.1V
117.2V
67.5 V
47.7 V
296.8V
157.1V
117.2V
87.4 V
28.0 V
+SC+SC
-SC-SC
Full depletion
RT Reverse Anneal in 9 month: -227 volts or-SC increasing rate: 0.062 /n-cm
Proton Radiation• TCT measurements (MCZ): 10 MeV protons, 3.0x1013 p/cm2
Laser on the p+ side (front side): +SC, DJ barely seen
8.4 V
291V
215V
• TCT measurements (MCZ): 10 MeV protons, 3.0x1013 p/cm2
Laser on the n+ side (back side): +SC, DJ barely seen
8.0 V
291V
215V
• TCT measurements (MCZ): 10 MeV protons, 5.9x1013 p/cm2
Laser on the p+ side (front side): close to 0 SC, DJ/DP seen
6.8 V
286V
134V
• TCT measurements (MCZ): 10 MeV protons, 5.9x1013 p/cm2
Laser on the n+ side (back side): 0 to - SC, DP seen
6.9 V
286V
134V
• TCT measurements (MCZ): 10 MeV protons, 1.2x1014 p/cm2
Laser on the p+ side (front side): - SC, DJ/DP clearly seen
6.6 V
474V
260V
• TCT measurements (MCZ): 10 MeV protons, 1.2x1014 p/cm2
Laser on the n+ side (back side): - SC, DP seen
83 V
865V
260V
• For MCZ Si detectors, SCSI takes place around 5.9x1013 p/cm2
after 10 MeV proton radiation.
• Double junction and double peak (DJ/DP) have been observed after SCSI
Proton Radiation (20 MeV)• TCT measurements (MCZ): 20 MeV protons, 3.0x1013 p/cm2
Laser on the p+ side (front side): +SC
8.5 V
295V225V
• TCT measurements (MCZ): 20 MeV protons, 3.0x1013 p/cm2
Laser on the n+ side (back side): +SC
8.5 V
295V
225V
• TCT measurements (MCZ): 20 MeV protons, 5.9x1013 p/cm2
Laser on the p+ side (front side): +SC
7.7 V
293V
225V
• TCT measurements (MCZ): 20 MeV protons, 5.9x1013 p/cm2
Laser on the n+ side (back side): +SC
7.7 V
293V
225V
• TCT measurements (MCZ): 20 MeV protons, 1.2x1014 p/cm2
Laser on the p+ side (front side): -SC, DJ/DP clearly seen
7.0 V
287V
188V
• TCT measurements (MCZ): 20 MeV protons, 1.2x1014 p/cm2
Laser on the n+ side (back side): -SC
86 V
876 V
188V
• For MCZ Si detectors, SCSI takes place between 5.9x1013
p/cm2 to 1.2x1014 p/cm2 after 20 MeV proton radiation.
• Double junction and double peak (DJ/DP) have been observed after SCSI
0 10 20 30 40 50
1 MeV equivalent n- Fluence (1E13 n/cm2)
-7-6-5-4-3-2-101234
(E12
)
Nef
f (1/
cm3)
CZ(b=0.017)n-rad
FZ(b=0.022)n-rad
CZ(b=0.0045)p-rad
CZ and FZ wafers
+SC
-SC
Space charge sign inversion (SCSI)
Comparison of Neff vs. 1 MeV equivalent n-fluence between neutron and proton radiations
o CZ Si detectors are slightly more rad-hard than FZ ones with n-rad βCZ (b in the figure) is about 23% less than βFZ
o CZ Si detectors are much more rad-hard than FZ ones with p-radβCZ is about 1/5 of βFZ and is about ½ of βOXYSCSI fluence is 3 time higher than that of FZ
• TCT measurements (MCZ): 20 MeV protons, 5.9x1013 p/cm2
Laser on the p+ side (front side): +SC
7.7 V
293V
225V
Reverse Anneal (8 month RTA)
93.9V
84.0V
74.1V
64.3V
54.5V
SCSI
44.8V
35.3V
25.9V
16.7V
7.7V
292.9V
263.0V
243.1V
223.2V
193.3V
SCSI
Full depletion
RT Reverse Anneal in 8 month: -176 volts or-SC increasing rate: 0.025 /p-cm Or 0.0096 /n-cm !
• TCT measurements (MCZ): 20 MeV protons, 5.9x1013 p/cm2
Laser on the n+ side (back side): +SC
7.7 V
293V
225V 44.8V
35.3V
25.9V
16.7V
7.7V
93.9V
84.0V
74.1V
64.3V
54.5V
292.9V
263.0V
243.1V
223.2V
193.3V
SCSI
Full depletion
Comparison and summary of radiation induced detectsIntroduction rate of stable defects
n/cm in and Mrad,in ( , equ-n 1MeVequ-n 1MeV ,,equ-n 1MeV ,, ΦΦΦΦ⋅= nornornef fN γγγβ
Detector Type
Gamma βγ (1/Mrad-cm3)
n (1 MeV) βn (1/n-cm)
Proton β1MeV n-equ (1/ n-cm)
CFZ
-1.82x109
-0.022
-----
MCZ
2.92x109
-0.017
-0.00045
(old) FZ
-8.0x109
-0.023
-0.0022
HTLT oxygenated
4.1x108
-0.023
-0.0094
Introduction rate of reverse anneal generated defects )n/cm in and ( , 2
equ-n 1MeVequ-n 1MeV equ-n 1MeV , ΦΦΦ⋅= nornornrevreveff
N β
Detector Type
n (1 MeV) βrev,n (1/n-cm)
Proton βrev, 1MeV n-equ
(1/ n-cm)
CFZ
-0.062
MCZ
-0.050
-0.0096
(old) FZ
-0.073
• With higher [O], MCZ Si has more un-activated TD’s• Produced during the TD killing process
• Gamma radiation activates those un-activated TD’s, giving rise to the higher positive SC build-up rate
• This positive SC build-up may also happen in charged particle irradiated MCZ Si detectors, giving possibility of compensating regular negative SC ---- improvement of rad-hardness
• The degree of this improvement in rad-hardness may depend type of particle radiation
• MCZ Si detectors are also more rad-hard than CFZ Si detectors in reverse annealing (Gettering effect by O) after p radiation
Summaryo Experimental results indicates that, upon gamma radiation, the MCZ Si detectors behave similarly to oxygenated Si detectors
Positive SC build-upNo SCSI
o The build-up rate positive SC in gamma irradiated Si detectors is higher than that in oxygenated Si detectors, and is proportional to [O]
Much higher [O] in MCZEven higher concentration of un-activated TD
o Gamma-induced activation of TD’s may be responsible
o MCZ Si detectors are also partially rad-hard to charge particles (protons in our case) and are more rad-hard than oxygenated Si detectors, and may be slightly radiation hard to neutrons than CFZ Si detectors. MCZ Si detectors are also more rad-hard than CFZ Si detectors in reverse annealing