Fluence dependent recombination lifetime in neutron and proton irradiated MCz , FZ and epi-Si structures
E.Gaubas, J.Vaitkus, T.Čeponis, A.Uleckas, J.Raisanen, S.Vayrynen, and E.Fretwurst
Vilnius University, Institute of Materials Science and Applied ResearchHelsinki University, Accelerator Laboratory
University Hamburg
Outline
Objectives of investigations
Samples, irradiations and experiments
Fluence dependent lifetime variations
Characteristics of lifetime cross-sectional profiles
Summary
Objectives / investigations
- Direct measurements of recombination lifetime fluence dependences:
comparative analysis of carrier decay in MCZ, FZ and epi-Si neutron irradiated structures
- Control of possible anneal of defects:
heat treatments 80C
- Recombination lifetime variations with energy of protons
- Recombination characteristics in 2 MeV proton irradiated n-FZ Si
combined investigations of MWR, DLTS and RR in 2MeV proton irradiated structures
- Cross-sectional scans within structure depth to control defect production profiles
Samples
Structures tested
1.9 and 2.0 MeV protons
200µm60µm
n+-Sin-Siρ=0,04 Ωcmρ=25 Ωcm
Apšvitos srautas
Diodes
Wafer structures
=41-49 m
|2 MeV=7 m
Irradiation plan March 2007 TRIGA reactor Resp. Gregorarrival HH 15-06-2007, 12:20 in cold box
Material: Wacker FZ <111> 2 kOhmcm 290 µm Process STM W337
W337phi_n [cm-2] FZ
1.00E+13 B11
1.00E+13 E81.00E+14 Q51.00E+14 G131.00E+15 H21.00E+15 H31.00E+16 Q61.00E+16 I13
Irradiation TRIGA reactor November 2006arrival HH: 8. January 2007, by Gregor
Material: ITME p-EPI <111> 150 Ohmcm 50 µm Process: CIS
260868-01 annealingp-EPI 80 °C V_dep [V]
phi_n [cm-2] 50 µm t_max [days] at t_max
3.00E+13 16 31.3 88.11.00E+14 19 31.3 52.83.00E+14 27 31.3 47.91.00E+15 33 31.3 89.03.00E+15 36 31.3 268.01.00E+16 41 2.3 671.0
not irradiated 43* x xnot irradiated 44* x x* breakdown voltage about 60 V, guard ring not working
Irradiation TRIGA reactor March 2004
Material: ITME n-EPI <111> 50 Ohmcm 50 µm Process: CIS
6336-04 annealingn-EPI 80 °C V_dep [V]
phi_n [cm-2] 50 µm t_max [days] at t_max
2.00E+14 06 135.3 59.06.00E+14 08 135.3 3.21.00E+15 11 135.3 18.72.00E+15 17 135.3 90.94.00E+15 24 148.4 240.88.00E+15 28 135.3 450.01.00E+16 32 135.3 478.0
not irradiated 34 x xnot irradiated 35 x x
1
2
Neutron irradiated
Proton irradiated
FZ
n- epi
FZ n-Si
p- epi
WODEAN
VU-HUAL
Mesaurements: MW-PCD,RR, C-DLTS
M
Neutron fluence dependent recombination lifetime in FZ and epi- Si
1013
1014
1015
1016
100
101
102
103non-irradiated
Fluence (cm-2)
Neutron irradiated FZ diodes n-epi diodes p-epi diodes
(n
s)
Lifetime in neutron irradiated Si under heat treatments at 80C
1012 1013 1014 1015 101610-4
10-3
10-2
10-1
100
101
Okmetic MCZ<100> 1kcm as-irradiated
Heat treated at Tann= 800 C
for tanneal = 5 min 30 min 24 h Waker W337 FZ diodes- un-annealed
n-epi diodes 800 C-long anneal
p-epi diodes 800 C-long anneal
Re
com
bin
atio
n li
fetim
e (s
)
Neutron fluence (n/cm2)
Fluence dependent lifetime variations in different particle energy irradiated structures
1012
1013
1014
1015
1016
10-1
100
101
102
103
104
Neutron irradiated material MCZ as-irradiated
Proton irradiated material MCZ RT -50 MeV sFZ RT - 24 GeV/c DOFZ RT - 24 GeV/c V- n- FZ 2 MeV
R (n
s)
Fluence (cm-2
)
100 150 200 250 3000
20
40
60
80
100
120
140
V-cluster (S.Watts)
V2
-/0
V2
=/-
A (V-O)
FZ n-Si diode V
1.9 MeV protons 7x1012 p/cm2
FZ n-Si diode CERN-Oslo
5 MeV electrons 1012 e/cm2
DL
S (
a.u
.)
T (K)
0 2 4 6 8 10
10-2
10-1
100
101
irradiation spot effective radius
- V FZ n-Sienergy of protons 2 MeV
fluence 7*1013
p/cm2
(s
)
x (mm)
1.9 and 2.0 MeV protons
200µm60µm
n+-Sin-Siρ=0,04 Ωcmρ=25 Ωcm
Apšvitos srautas
Wafer structures
=41-49 m
20 mm
20 mmReff
Lateral lifetime variation
0 10 20 30 40 500
20
40
60
80
100
120
140
VVP Si Tomas`Proton energy 2 MeV
fluence 4*1014
p/cm2
(ns)
x (m)
MW-PCD-depth – scans
in 2 MeV protons irradiated FZ n-Si
0 10 20 30 40 500.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5V FZ n-Si Proton energy 2 MeV
fluence 4*1014 p/cm2
Am
plit
ude (
a.u
.)
x (m)
0 1 2 3 4 5 610
-3
10-2
10-1
100
UM
WR
(a.u
)
t s)
VVP Si TomoProton energy 2 MeV
fluence 4*1014
p/cm2
x = 40,0 m = 0,065 s = 1,1 s
200µm60µm
n+-Sin-Siρ=0,04 Ωcmρ=25 Ωcm
Apšvitos srautas
0.0 0.1 0.2 0.30
1
2
UM
WR
(a.u
)
t s)
VVP Si TomoProton energy 2 MeV
fluence 4*1014
p/cm2
x= 1 m x= 40 m
Cross-sectional scans within depth of neutron irradiated wafer
fiber
MW coaxial needle-tipantenna
sample
0 100 200 30010
0
101
102
103
MCZ 1 k·cm, d= 300 m neutron fluence
1012
cm-2
3·1014
cm-2
1015
cm-2
3·1015
cm-2
MWR amplitude R(n
s),
MW
R a
mpl
itude
(a.
u.)
Z (m)
Fluence dependent variations of
MW-PCD, DLTS and RR characteristics
in 2 MeV protons irradiated FZ n-Si
100 150 200 250 300
0,2
0,4
0,6
0,8
1,0
1,2cluster edge &/or H-?
V2
-/0
V2
=/-
V-O-?
non-irradiated2 MeV protons irradiated
7E12 p/cm2
7E13 p/cm2
7E14 p/cm2
DL
S (
a.u
.)
T (K)
1013 10140
400
800
1200
1600
2000
2 MeV protons
RR, n
s
, cm-2
IF=0.5A
IF=1A
IF=2A
IF=4A
IF=6A
IF=8A
IF=10A
1013
1014
1015
100
101
102
2 MeV protons FZ n-Si wafers/diodes
R (
ns)
Fluence (p/cm2)
SUMMARY
Lifetime decreases from few s to about of 200 ps with enhancement of neutron irradiation fluence ranging from 1012 to 31016 n/cm2, as measured directly by exploiting microwave probed photoconductivity transients and verified by dynamic grating technique.
Lifetime values are nearly the same for neutron irradiated wafer and diode samples. These values are close to that in >20 MeV proton irradiated various Si diodes.
Small increase of lifetime values under annealing can be implied.
Lifetime values are nearly invariable within wafer thickness for high energy neutrons, while the lifetime depth profile is inhomogeneous for 2 MeV protons irradiated structures.
Production of recombination defects in ~2 MeV protons irradiated FZ Si is efficient, and lifetime depth profiles correlate with stopping range of particles.
Thank You for attention!
Clusters
V2
V2
V2
V2
V2
V2
V2
V2
V2
V2
V2
V2 V
2
PD
V2 V
2
V2
V2
V2
V2
V2
V2
V2
V2
V2
V2 V
2
V2 V
2
V2
V2V
2 V2 V
2 V2 V
2
V2
V2
V2
V2 V
2 V2
V2
V2
V2
V2 V
2 V2 V
2
V2 V
2
V2 V
2
Fluence
Measurement techniques and instruments
Dynamic gratings (DG)
Diffraction efficiency (=I-1/I0) on light induced dynamic grating is a measure (N)2 of excess carrier density, while its variations in time (t) exp(-2t/G) by changing a grating spacing () enable one to evaluate directly the parameters of grating erase 1/G = 1/R + 1/D through carrier recombination (R) and diffusion D = 2/(42D) with D as a carrier diffusion coefficient.
K.Jarasiunas, J.Vaitkus, E.Gaubas, et al. IEEE Journ. QE, QE-22, (1986) 1298.
Microwave probed photoconductivity (MW-PCD)
in MW reflection mode (MWR)
k
E
cw MW probe
laser lightpulsed excitation R
kk
E
cw MW probe
laser lightpulsed excitation R
MWR >100m 0 =(4/c )dc, transient:(t) (t) FC nexFC (t)
(t)
E.Gaubas. Lith. J. Phys., 43 (2003) 145.
Rload
MB tiltas
MW oscillatorwith adjustable power
and frequency
MB cirkulatorius
MB tiltas
MW circulator
f0.5 GHz,U1 mV/pdf0.5 GHz,U1 mV/pd
TDS-5104
Microchip laser STA-01
exc ~700 ps, Eexc 10 J
MW slitantenna
sample
MW bridge
Attenuatorof light density Sliding short
Sliding short
Sliding short
Amplifier (>50)
MW detector
Rload
MB tiltas
MW oscillatorwith adjustable power
and frequency
MB cirkulatorius
MB tiltas
MW circulator
f0.5 GHz,U1 mV/pdf0.5 GHz,U1 mV/pd
TDS-5104
Microchip laser STA-01
exc ~700 ps, Eexc 10 J
MW slitantenna
sample
MW bridge
Attenuatorof light density Sliding short
Sliding short
Sliding short
Amplifier (>50)
MW detector
MB tiltasMB tiltas
MW oscillatorwith adjustable power
and frequency
MW oscillatorwith adjustable power
and frequency
MB cirkulatorius
MB tiltas
MW circulator
f0.5 GHz,U1 mV/pdf0.5 GHz,U1 mV/pd
TDS-5104
Microchip laser STA-01
exc ~700 ps, Eexc 10 J
Microchip laser STA-01
exc ~700 ps, Eexc 10 J
MW slitantenna
sample
MW bridge
Attenuatorof light density Sliding short
Sliding short
Sliding short
Amplifier (>50)
MW detector
The microwave probed photoconductivity (MW-PCD) technique is based on the direct measurements of the carrier decay transients by employing MW absorption by excess free carriers. Carriers are photoexcited by 1062 nm light generated by pulsed (700 ps) laser and probed by 22 GHz cw microwave probe.
MW instruments at VU
Lateral mappingCross-sectional scan
Recombination lifetime in wafer and diode samples measured by MWR
1012 1013 1014 1015 1016
10-4
10-3
10-2
10-1
100
Okmetic MCZ<100> 1kOhm·cm 300 m MWR, CIS 8556- 14 wafers 1 - 63 passivated CIS 8556- 14 wafers measured by DG technique CIS 8556-01 diodes neutron irradiated
1/ R
(n
s-1)
Fluence (n/cm2)
1012 1013 1014 1015 101610-4
10-3
10-2
10-1
100
101
=1
Okmetic MCZ<100> 1kOhm·cm 300 m non-processed CISSamples 8556- 14 1 - 63 passivated wafers
- directly measured values &extracted from the decrease of amplitude UMWR
wafers 54-60 measured by DG
R
-1 (
ns-1)
Fluence (n/cm2)
Neutron fluence dependent recombination lifetime in MCZ Si
0 5 10 150
5
10
15
20
- H1-1012 n/cm2
-H61
- H2-1013 n/cm2
- H62
- H3-1014 n/cm2
- H63
- H4-3·1014
n/cm2
- H64
- H53-1015
n/cm2
- H54
- H55-3·1015
n/cm2
- H56
- H57-1016
n/cm2
- H58
- H59-3·1016
n/cm2
- H60
UM
WR (
a.u
.)
t (s)
R t|U ~ exp(-1)
R gexcRs/gexcRL (UMWRs<2 ns /UMWRL>5 ns)
1012 1013 1014 1015 1016
10-1
100
101
102
103
104
Laser pulse limit
Electr. circuitry limit
Okmetic MCZ<100> 1kOhm·cm 300 m non-processed CISSamples 8556- 14 1 - 63
- directly measured values - extracted from the decrease of amplitude U
MWR
Eff
ect
ive
life
time
(n
s)Neutron fluence (cm
-2)
Combined direct techniques