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



10 V

394 V

208V

Gamma Radiation

197 V

499 V

248 V



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


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


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



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


99.8 V

993 V

750 V


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


Laser on the p+ side (front side): -SC & DJ/DP

78 V

629 V

520V



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


89 V

569 V

320V



89 V

383 V

320V


Laser on the p+ side (front side): -SC (only front junction seen)

79 V

767V

320V


Laser on the n+ side (back side): -SC (only one junction seen)

76 V

769 V

430 V



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


Laser on the p+ side (front side): +SC

8.8 V

297 V

160V



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


Laser on the p+ side (front side): close to 0 SC, DJ/DP seen

6.8 V

286V

134V


Laser on the n+ side (back side): 0 to - SC, DP seen

6.9 V

286V

134V


Laser on the p+ side (front side): - SC, DJ/DP clearly seen

6.6 V

474V

260V


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.


Proton Radiation (20 MeV)• TCT measurements (MCZ): 20 MeV protons, 3.0x1013 p/cm2


8.5 V

295V225V



8.5 V

295V

225V



7.7 V

293V

225V



7.7 V

293V

225V


Laser on the p+ side (front side): -SC, DJ/DP clearly seen

7.0 V

287V

188V



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.


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



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 !



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

Radiation Hardness of High Resistivity CZ Si Detectors ... · 99.7 V 846 V 767 V •TCT...

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