TSC results - University of Hamburg

I. Pintiliea),b), E. Fretwurstb), G. Lindströmb) J. Stahl b) and F. Hoenniger b)

 a)National Institute of Materials Physics, Bucharest-Magurele, P.O.Box MG-7, Romania b)Institute for Experimental Physics, Hamburg University, D-22761, Germany

Publications• I. Pintilie, E. Fretwurst, G. Lindstroem and J. Stahl, Appl. Phys. Lett. 81, No 1 (2002) 165• I. Pintilie, E. Fretwurst, G. Lindstroem and J. Stahl, Appl. Phys. Lett. 82, No 13 (2003) 2169• I. Pintilie, E. Fretwurst, G. Kramberger, G. Lindstroem, Z. Li and J. Stahl, Physica B: Condensed Matter 340-342 (2003) 578• I. Pintilie., E. Fretwurst, G. Lindstroem and J. Stahl, Nucl. Instr. and Meth. A 514 (2003) 18• G. Lindstroem, E. Fretwurst, G. Kramberger, I. Pintilie, Journal of Optoelectronics and Advanced Materials Vol. 6, No. 1, (2004) 23• J. Stahl, E. Fretwurst, G. Lindstroem and I. Pintilie, Physica B: Condensed Matter 340-342 (2003) 705• I. Pintilie, L. Pintilie, M. Moll, E. Fretwurst and G. Lindstroem, Appl. Phys. Lett 78 (2001) 550 • J. Stahl, PhD Thesis, Hamburg University, 2004, DESY-Thesis-2004-28, ISSN 1435-8085 • E. Fretwurst, G. Lindstroem, J. Stahl, I. Pintilie, Z. Li, J. Kierstead, E. Verbitskaya and R. Röder, Nucl. Instr. and Meth. A 514 (2003) 1-8

•     Material:- STFZ, DOFZ, Cz and EPI (25, 50, 75 m)

diodes- p+nn+ Si diodes, processed by CiS/Erfurt

Germany

• Irradiation: - Co60 -source at BNL, dose range 90 to 500 Mrad

- CERN (24 GeV protons) up to 6x1014/cm2

• Measurements:• C-V, I-V, at RT• Thermally Stimulated Current

0 10 20 30 40 50 60 70 80 90 100Depth [m]

51016

51017

51018

5

O-c

once

ntra

tion

[cm

-3]

SIMS 25 m SIMS 25 m

25 m

u25

mu

SIMS 50 mSIMS 50 m

50 m

u50

mu

SIMS 75 mSIMS 75 m

75 m

u75

mu

simulation 25 msimulation 25 msimulation 50 msimulation 50 msimulation 75msimulation 75m

Sample STFZ DOFZ EPI/Cz (50 m)

Cz

SIMS [O] <5*1016 1.2*1017

9*1016

8.1*1017

Detected Trapping levels

No Level Method Ea(eV)

n/p

10-15cm2

Material Obs.

1 H(42K) TSC +0.084  /0.5  DOFZ, Cz, Epi 150C-an-out

2 H(47K) TSC  +0.1  /1 DOFZ, Cz, Epi  

3 E(50K) TSC  -0.11  2  DOFZ, Cz, Epi 150C-an-out, IO2

4 VO-/0 DLTS, TSC        less in STFZ

5 H(87K) TSC  +0.2 /2  DOFZ, Cz, Epi after 150C ann.

6 I+/0 TSC  +0.225  /1  

7 BD(98K) TSC  -0.225   DOFZ, Cz, Epi Bistable donor -TDD

8 VV=/- DLTS        

9 CiOi+/0 DLTS,TSC        

10 E(147K) TSC        

11 VV-/0 DLTS,TSC        

12 I0/- DLTS,TSC 0.545/+0.58

 2/90    suppressed in DOFZ, V2O

13 DLTS,TSC  +0.66  0.05/5    suppressed in DOFZ

-0.37 2.5

+0.36 /2.3

-0.215 0.1

 -0.17  14

-0.42 2

A) Co60- irradiation (96-500 Mrad doses)

50 100 150 200 250-5

0

5

10

15

20

25

30

35

40RB = 300 V

CiOi+/0

H(97K)

VO-/0

+ CiCs

H(240K)

IH(V

2O?)

STFZ 96 Mrad 190 Mrad 245 Mrad 284 Mrad

TS

Curr

ent (p

A)

Temperature (K)

50 100 150 200 250

0

20

40

E(50K)

RB = 300 V

H

Ih (V

2O?)

CiOi

H(97K)

VOi + CiCs

BD tail

284 Mrad dose STFZ DOFZ

TS

Cur

rent

(pA

)

Temperature (K)

STFZ:-H(97K)-more I-more

DOFZ:

-BD tail + E(50K)

-more VOi100 1000

1011

1012

STFZ

I(200K): I0/-

H(97K): I+/0

slope 1.96DOFZ

I(200K): I0/-

slope 1.98

Con

cent

ratio

n of

def

ects

(cm

-3)

Dose (Mrad)

•I defect - almost quadratic dose dependence defect formed through a second order procces (VO+V?)

• DOFZ – different experimental procedures

50 100 150 200 250

0

10

20

30

40

50

BD

H(240K)

IH(V

2O

0/-)CiOi

+/0

BD(98K)

VO-/0

E(50K)

H(42K)

DOFZ - 245 Mrad: Cooling from RT under 0 V after: exposure to day light keeping in dark at RT for 2 days

TS

Curr

ent (p

A)

Temperature (K)

TDD1 and TDD2 in n type Si are bistable thermal donors (BTD) – they can exist also in a configuration which forms an Anderson negative U-system

Donor activity of BD(98K) centers

60 80 100

0.1

1

10

Forward injection at 20 K

VO-/0

BD(98K)

DOFZ - 245 Mrad 100 V 300 V 500 V

TS

Cur

rent

(pA

)

Temperature (K)

If the Poole Frenkel effect is present a shift of TSC peak to lower T should be seen when increasing the applied bias

10.0 10.5 11.0 11.5 12.0 12.5

0.1

1

RB = 500 V; EaTSC

= 0.128 eV

RB = 300 V; EaTSC

= 0.139 eV

RB = 100 V; EaTSC

= 0.160 eV

TSC

urre

nt (p

A)

1000/T (K-1)

H = 0.225 eV - 0.00206xV1/4

Gamma irradiation -Influence of I, and BD defects on

detector properties

0 50 100 150 200 250 300

0

40

80

120

160

200

240

280293 Kfrom I - V

DOFZ STFZ

calculated (I& levels) DOFZ (errors > 5%) STFZ (errors < 5%)

LC

(nA

)

Co60- gamma irradiation dose

excellent agreement with the I-V and C-V results at RT!

0 50 100 150 200 250 300-1.4x10

12

-1.2x1012

-1.0x1012

-8.0x1011

-6.0x1011

-4.0x1011

-2.0x1011

0.0293 K

from C-V DOFZ STFZ

calculated DOFZ (errors > 5%) STFZ (errors < 5%)

Nef

f (cm

-3)

Co60- gamma irradiation dose

volTnTeqTLC

TnTN

En

Eeff

)()()(

)()(

0

High temperature annealing studies

40 60 80 100 120 140 160 180 200-5

0

5

10

15

20

25

30

35

40

45

b)

Isothermal annealing at 300 0C - hole traps

960 min

H(172K)

CiOi+/0

460 min

220 min460 min

I+/0

+ H(0.24eV)

220 min

H(70K)

I0/-

not annealed 220 min 460 min 960 min 2400 min

TS

C s

igna

l (pA

)

Temperature (K)

I center – stable at 300 0C for the first 460 min

STFZ

I) The I defect

II) The X center

• STFZ – 300 Mrad

40 60 80 100 120 140 160 180

0

20

40

60

80

100

a)

Isothermal annealing at 300 0C - electron traps

VO-/0+CiCs-/0

E(147K)

VV-/0

+ X-/0

2400 min0 min

10 min

not annealed 2.5 min 7.5 min 100 min 960 min 2400 min

TSC

sig

nal (

pA)

Temperature (K)0 500 1000 1500 2000 2500

0.1

1

10

I center VV X CiCs + VOmin/10

H(0.24)* H(172K)

Def

ect c

once

ntra

tions

(10

11cm

-3)

Annealing time (min)

In STFZ material the formation of X center is independent on the annealing of V2

• Epi/Cz - same irradiation dose (520 Mrad) and annealing at different T

80 100 120 140 160 180 200

0

5

10

15

20

25

V2

=/-

X-/0

V2

=/-

X=/-

TS

C s

ignal (

pA

)

Temperature (K)

0 min @ 320C 10 min @ 320C 20 min @ 320C 40 min @ 320C 80 min @ 320C 160 min @ 320C

T = 3200C

T = 3000C

Increasing the annealing temperature [X] increases althougth [V2] is the same The contribution of other defect/impurity becomes important at high T

80 100 120 140 160 180 200

0

5

10

15

20

25

V2

=/-

X=/-

X-/0

V2

-/0

TS

C s

ignal (

pA

)

Temperature (K)

30min@200C 40min@300C 60min@300C 160 min@300C 240min@300C 440min@300C 1220min@300C

80 85 90 95 100 105 1100

2

4

6

8

holes injection - volume ~ 3.5 times smaller than for electron injection

X+/0

TS

Curr

ent (p

A)

Temperature (K)

0 min 10 min 20 min 40 min 80 min 160 min 340 min

T = 300 0C

Dose = 305 Mrad Dose = 520 Mrad

Increasing the irradiation dose [X] increases more than the initial [V2] the involvement of other radiation induced defect (like VO center) in the formation of X centers is possible

80 100 120 140 160 180 200

0

5

10

15

20

V2

=/-

X=/-

X-/0

V2

-/0

TS

C s

ignal (

pA

)

Temperature (K)

30min@200C 40min@300C 60min@300C 160 min@300C 240min@300C 440min@300C 1220min@300C

80 100 120 140 160 180 200

0

5

10

15

20

V2

=/-

X=/-

X-/0

V2

-/0

TS

C s

igna

l (pA

)

Temperature (K)

30min@200C 60min@300C 80 min@300C 160min@300C 440 min@300C 560min@300C 1220min@300C

• Epi/Cz - same annealing T but different irradiation doses

100 120 140 160 180

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

V2+ clusters

CiO

i

BDA

TS

C n

orm

aliz

ed s

igna

l (pA

/m

)

Temperature (K)

75 m 50 m 25 m

B) 23 GeV proton irradiation (fluences up to 6x1014/cm2)

20 30 40 50 60 70 80 90 100

0

20

40

60

80

100

120

140

VO -/0

IO2

-/0

BD0/++

BD tail (+/++)

TS

Cu

rre

nt (

pA

)

Temperature (K)

CZ - not annealed after exposure to day light after 5 days keeping in dark at RT

The BD and I defect concentrations can explain ~90% from Neff ~10% of the LC

Summary

Co60 – gammas: the radiation induced change of detector properties is understood on the basis of generated defect levels • Two defects the BD and the I-defect are mainly responsible for the macroscopic performance of the diodes- The I centers (acceptor like at RT) are the source for both introduction of negative space charge and the increase of the LC- The BD defects are the source for the increase of the positive space charge with the dose in DOFZ diodes and can compensate the deep acceptors effect

24 GeV proton irradiation:• Very promising results in the case of EPI/Cz silicon – most likely due to a large concentration of oxygen dimers migrating from the CZ substrate

Future plans:

Investigation of BD, I and X centers after high levels of Co60-gamma and 23 GeV proton irradiation in:

- 150 cm standard and oxygenated Epi/Cz (n and p-type, 70, 100 and 150 m )

- 100 cm FZ silicon (50 m)