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INTERACTION OF RESIDUAL HYDROGEN WITH RADIATION
DEFECTS IN SILICON PARTICLE DETECTORS
L.F. Makarenko*, F.P. Korshunov**, S.B. Lastovski**, N.M. Kazuchits*, M.S. Rusetsky*,
E. Fretwurst***, G. Lindström***, M. Moll****, I. Pintilie*****, N.I. Zamiatin******
* Belarusian State University, Minsk, Belarus
**Institute of Solid State and Semiconductor Physics, Minsk, Belarus
***Hamburg University, Hamburg, Germany
****CERN, Geneva, Switzerland
*****National Institute of Materials Physics, Bucharest-Magurele, Romania
******Joint Institute for Nuclear Research, Dubna, Russia
1. Introduction
It is well-known that hydrogen can easily penetrate into silicon crystals at various stages of p-n structures manu-
facturing. Therefore possibly all silicon particle detectors contain hydrogen which remained in these structures after
fabrication. There are some indications on interaction of residual hydrogen with defects in irradiated Si detectors. It is
expected that the increase of hydrogen content will lead to the increase of radiation tolerance of devices. It may be
due to, first, hydrogen passivation of radiation defects, and, second, acceleration of oxygen diffusion by promoting
the formation of oxygen dimer О2.
Both high mobility and reaction ability of hydrogen result in its redistribution during subsequent technological
processes occurring even at rather low temperatures 200-400 °С. Therefore one expects that concentration of hydro-
gen in various areas of detectors will depend substantially on sequence of technological operations of their manufac-
turing and now there is not enough information on hydrogen in ready detector structures. It is the aim of this work to
get experimental data on hydrogen content and distribution in p+-n-n+ structures made of detector grade silicon and
influence of hydrogen on elimination of electrically-active radiation defects.
2. Experimental
Detector structures were manufactured from standard n-type Wacker Si by the following producers: 1) CiS Insti-
tute for Microsensors, Erfurt, Germany (CA-diodes); 2) ST Microelectronics, Catania, Italy (W336-diodes); 3)
ELMA, Zelenograd, Russia (Z-diodes). Simple p+-n-n+ structures with a guard rings were employed. The Z diodes
were prepared are by the same technology as for the CMS preshower sensors.
Table 1. Parameters of samples used for experiments
Device
acronym
Thickness,
µm
Starting resistivity,
KΩ⋅cm
Orientation Rear contact
CA 285 4 <111> grid
W336 290 2 <111> grid
Z 330 4 <111> block
Hydrogenation was performed using treatment in hydrogen plasma at T=300 °C during 0.5-4 hours. Glow dis-
charge plasma of hydrogen was created using a discharge chamber of the standard facility for the ionic etching . The
discharge dc voltage was 500 V. The density of the plasma current was 3-5 µA/cm2 that corresponded to density of
ion current about 2×1012 cm-2⋅s-1. Samples were arranged on a surface of a heater located in the discharge chamber.
The control of temperature was carried out with the help of the thermocouple which was in contact to a control sam-
ple of the same thickness.
1 – H+ plasma
2 – anode
3 – sample
4 – thermocouple
5 – heat shield
6 – heater in a bulb
Irradiation with electrons (E=3.5 or 6 MeV) was done using accelerators at the Institute of Solid State and Semi-
conductor Physics (Minsk). The irradiated samples were subjected to 30 min isochronal annealing in the temperature
range 50-350 °C with temperature increments of 50 °C.
Defect reactions have been studied using capacitance deep level transient spectroscopy (DLTS) (Tmeas=77-325 K)
and high frequency capacitance-voltage (C-V) measurements at room temperature. The experimental equipment con-
sisted of a capacitance meter, a HF-generator (1 MHz), a DC source and a pulse generator, and personal computers,
which controlled the pulse generator and performed the data acquisition. Possible variations of the reverse bias and
the rate window are up to 19 V and the rate window 4-19000 s-1, respectively. Normally both the reverse bias and the
pulse voltage were 5 V, and the rate window setting was 190 s-1.
Capacitance-voltage measurements are carried out with a digital capacitance bridge. The capacitance has been
measured at different reverse bias values by superimposing an ac voltage on the dc voltage. The reverse bias is typi-
cally varied in the range VR = 0-150 V in steps of 0.045-0:135 V. The amplitude and the frequency of the ac voltage
were 25 mV and 1 MHz, respectively. The measurements are controlled by home-developed Pascal program with
custom made instrument interface.
Table 1. Parameters of dominant peaks
Peak
number
Tmax, K
(at en=190 s-1)
A, s-1K-2 σA, cm2 EA, eV Peak origin
E1 94 3.9 107 6 10-15 0.174 VO+CiCs
E2 133 1.9 107 3.1 10-15 0.246 VV=
E3 ∼192 1.3 107 2 10-15(?) 0.358(?) Stable up 100-150 °C
E4a 230 7.5 106 1.1 10-15 0.423 VV−
E5 174 9.6 106 1.5 10-15 0.314 VOH
E6 111 1.9 105 2.9 10-17 0.163
E7 146 8.2 105 1.2 10-16(?) 0.238(?) ?
E8 198 5.9 106 0.9 10-15 0.356 ?
E9 186 9.1 104 1.4 10-17(?) 0.269(?)
E10 276 3.8 105 6.1 10-17(?) 0.51(?)
Fig.1a. Development of DLTSspectra for standard FZ diodes(CA-sample) after electron irra-diation at room temperature andupon 30-min isochronal an-nealing with temperature in-crements of 50 °C. Dose of ir-radiation was 2×1012 cm-2
(Ee=3.5 MeV). Measurementsettings wereen = 190 s-1,bias –5 → 0 V, andpulse duration =10 ms.
80 100 120 140 160 180 200 220 240 260 2800
50
100
150
200
250
300
350
400
450
500
550
600
as-irradiated 250 oC anneal 300 oC anneal
S,
fF
T, K
x1/3 aE1
E2
E3
E4
Fig.1b. Development of DLTS spec-tra for standard FZ diodes (W-sample) after electron irradiation atroom temperature and upon 30-minisochronal annealing with tempera-ture increments of 50 °C. Dose of ir-radiation was 2×1012 cm-2 (Ee=6MeV). Measurement settings wereen = 190 s-1,bias –5 → 0 V, andpulse duration =10 ms
80 100 120 140 160 180 200 220 240 260 2800
40
80
120
160
200
240
280
320
360
400
440
b as-irradiated 250 oC anneal 300 oC anneal
T, K
S, fF
E1
E2
E3
E4
E5
Fig.1c. Development of DLTSspectra for standard FZ diodes(ZA-sample) after electron irra-diation at room temperature andupon 30-min isochronal an-nealing with temperature in-crements of 50 °C. Dose of ir-radiation was 1×1012 cm-2 (Ee=6MeV). Measurement settingswereen = 190 s-1,bias –5 → 0 V, andpulse duration =10 ms
80 100 120 140 160 180 200 220 240 2600
1
2
3
4
5
6
7
8
9
10
11
12
13
14 E1
as-irradiated 250 oC anneal 300 oC anneal
∆C
/C0,
0.1
%
T, K
c
E2
E3
E4E5
Fig. 2. DLTS spectra for different
diodes made of standard FZ sili-
con after isochronal annealing at
temperature 350 °C during 30
min. Measurement settings were
en = 190 s-1,
bias –5 → 0 V, and
pulse duration (tp) - 10 ms
80 100 120 140 160 180 200 220 240 260 280 3000
40
80
120
160
200
240
280
320
360
E6 CA0419an350 W336#-8an350 ZamA4an350
S,
fF
T, K
E1
E5
E8E9
E10
Fig.3. DLTS spectra for stan-
dard FZ diode (CA-sample) af-
ter isochronal annealing at tem-
perature 350 °C. Measurement
settings were en = 19 s-1, bias –5
→ 0 V, and pulse duration (tp):
0.1 ms, 1 ms, 10 ms, 100 ms.
80 100 120 140 160 180 200 220 240 260 280 3000
40
80
120
160
200
240
280
320
360
400
440
480
tp=1e2 tp=1e3 tp=1e4 tp=1e5
S,
fF
T, K
E1
E6
E5
E8E7 E10
hidden peak
Fig.4. Annealing behavior of
divacancy (trap E2) in different
diodes irradiated with electrons
or gamma-rays (W336 diodes).
50 100 150 200 250 300 350 4000.0
0.2
0.4
0.6
0.8
1.0
ZA4 e ZB2 e W336#10 γ W336#8 e Ca0434 e
[V
V]/[V
V]as
-irr
Tann, oC
Fig.5. DLTS spectra for stan-
dard FZ diode (CA-sample)
after irradiation with 3.5 MeV
electrons at room temperature
and upon 30-min annealing at
350 °C.. Dose of irradiation
was 3×1012 cm-2. Measure-
ment settings were: rate win-
dow of 190 s-1, pulse duration
of 10 ms, bias: a) -5 → 0 V, b)
−10→ −5 V and c) −19→ −15
V. The peak amplitudes are
normalized assuming constant
concentration of E8 trap.80 100 120 140 160 180 200 220 240
0
40
80
120
160
200
240
280
320
360
V=-5 V (filling pulse 5v) V=-10 V (filling pulse 5v) V=-19 V (filling pulse 4v)
S,
fF
T, K
E1 E6
E5
E8
Fig 6. Carrier depth profile for a
CA sample determined from C-
V characteristics.
Vertical lines mark inverse
voltage which is necessary to
obtain corresponded width of
depletion region.
0 40 80 120 160 200 240 280
8.0x1011
1.2x1012
1.6x1012
2.0x1012
2.4x1012
10 V
Nd(
x), c
m-3
depth, µm
1 - 100 oC anneal2 - 300 oC anneal3 - 350 oC anneal
5 V 15 V20 V0 V
1
2
3
Fig. 7. Development of DLTS
spectra for hydrogenated standard
FZ diode(CA-sample) after irradia-
tion with 3.5 MeV electrons at room
temperature and upon 30-min iso-
chronal annealing with temperature
increments of 50 °C. Dose of irra-
diation was 3×1012 cm-2. Measure-
ment settings were en = 190 s-1, bias
–5 → -0 V, and pulse duration 10
ms.
120 140 160 180 200 220 240 2600
40
80
120
160
200
240
280
320
360
400
asIRR ann100 ann150 ann250 ann300S,
fF
T, K
Fig.8. DLTS spectra for hydro-
genated standard FZ diode(CA-
sample) after irradiation with 3.5
MeV electrons at room tempera-
ture and upon 30-min annealing
at 300 °C. Dose of irradiation
was 3×1012 cm-2. Measurement
settings were en = 190 s-1, pulse
duration 10 ms bias: a) -5 → 0 V,
b) −10→ −5 V, b) −15→ −10 V.
All spectra normalized the E5
peak (VOH) amplitude.
80 100 120 140 160 180 200 220 240 260 280 3000
50
100
150
200
250
300
350
-5 V ->0 V -10 V ->5 V -15 V ->10 V
S,
fF
T,K
Fig.9. Carrier depth profile for a
CA sample determined from C-V
characteristics. Vertical lines mark
inverse voltage which is necessary
to obtain indicated width of deple-
tion region.
0 20 40 60 80 100 120 140 160 180 200 220 240 260 2801.0x1012
1.1x1012
1.2x1012
1.3x1012
1.4x1012
1.5x1012
1.6x1012
1.7x1012
1.8x1012
1.9x1012
2.0x1012
CA0419asPREP CA0419ann250 Ca0419an300
Nd(
x), c
m-3
depth, µm
5 V10 V
15 V
20 V0 V
Fig.10. Diffusion length for dif-
ferent hydrogen forms
(monoatomic H and H dimer) in
silicon calculated for 30 min
time period. Points shows our
estimations from the depth of
donor formation in nonhydro-
genated (Fig.6) and hydrogen-
ated (Fig.9) samples.
200 240 280 320 360 4001
10
100
from Fig.6
Newman TD H1 (vanWieringen&Warmoltz) H2 (Markevich)
L di
if, µm
temperature, oC
H1
H2
from Fig.9
Conclusions
Hydrogen may exist in different regions of silicon particle detector.When it is present in the base region of a diode then it interacts with radiation defects alreadyat temperatures of 100-150 °C.
When hydrogen is present at Si-SiO2 boundary or in strongly doped regions then its activationtemperature is in the range of 250-350 °C. At these temperatures hydrogen can penetrate inthe base region at the depth of 50-100 µm during 30 min and its penetration depth depends onthe form of diffusing hydrogen particles (H or H2)
It is a procedure of diode processing that influence on hydrogen distribution in silicon detec-tors of particles.
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