Photoelectric properties of single crystals Ag₃In₅Se₉
Low-resistance and high-resistance single crystals of Ag₃In₅Se₉ compound have been grown using the methods of zone recrystallization and slow cooling at a constant gradient of temperature. We have investigated spectral and lux-ampere characteristics of photoconductivity and determined the mechanism...
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| Дата: | 2006 |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2006
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| Цитувати: | Photoelectric properties of single crystals Ag₃In₅Se₉ / A.H. Huseynov, R.M. Mamedov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 25-28. — Бібліогр.: 7 назв. — англ. |
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Huseynov, A.H. Mamedov, R.M. 2017-06-15T03:05:07Z 2017-06-15T03:05:07Z 2006 Photoelectric properties of single crystals Ag₃In₅Se₉ / A.H. Huseynov, R.M. Mamedov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 25-28. — Бібліогр.: 7 назв. — англ. 1560-8034 PACS 72.40.+w https://nasplib.isofts.kiev.ua/handle/123456789/121614 Low-resistance and high-resistance single crystals of Ag₃In₅Se₉ compound have been grown using the methods of zone recrystallization and slow cooling at a constant gradient of temperature. We have investigated spectral and lux-ampere characteristics of photoconductivity and determined the mechanism of recombination inherent to non-equilibrium current carriers. It has been ascertained that the capture of electrons emitted by donor centers is caused by a strong electric field applied to a sample. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Photoelectric properties of single crystals Ag₃In₅Se₉ Article published earlier |
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Photoelectric properties of single crystals Ag₃In₅Se₉ |
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Photoelectric properties of single crystals Ag₃In₅Se₉ Huseynov, A.H. Mamedov, R.M. |
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Photoelectric properties of single crystals Ag₃In₅Se₉ |
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Photoelectric properties of single crystals Ag₃In₅Se₉ |
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Photoelectric properties of single crystals Ag₃In₅Se₉ |
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Photoelectric properties of single crystals Ag₃In₅Se₉ |
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photoelectric properties of single crystals ag₃in₅se₉ |
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Huseynov, A.H. Mamedov, R.M. |
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Huseynov, A.H. Mamedov, R.M. |
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2006 |
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English |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Article |
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Low-resistance and high-resistance single crystals of Ag₃In₅Se₉ compound have been grown using the methods of zone recrystallization and slow cooling at a constant gradient of temperature. We have investigated spectral and lux-ampere characteristics of photoconductivity and determined the mechanism of recombination inherent to non-equilibrium current carriers. It has been ascertained that the capture of electrons emitted by donor centers is caused by a strong electric field applied to a sample.
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1560-8034 |
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https://nasplib.isofts.kiev.ua/handle/123456789/121614 |
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Photoelectric properties of single crystals Ag₃In₅Se₉ / A.H. Huseynov, R.M. Mamedov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 25-28. — Бібліогр.: 7 назв. — англ. |
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AT huseynovah photoelectricpropertiesofsinglecrystalsag3in5se9 AT mamedovrm photoelectricpropertiesofsinglecrystalsag3in5se9 |
| first_indexed |
2025-11-26T22:51:04Z |
| last_indexed |
2025-11-26T22:51:04Z |
| _version_ |
1850779037262151680 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 25-28.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
25
PACS 72.40.+w
Photoelectric properties of single crystals 953 SeInAg
A.H. Huseynov, R.M. Mamedov
Baku State University, Department of Physics,
Z. Khalilov str., 23, AZ-1148 Baku, Azerbaijan
E-mail: rovshan63@rambler.ru
Abstract. Low-resistance and high-resistance single crystals of Ag3In5Se9 compound
have been grown using the methods of zone recrystallization and slow cooling at a
constant gradient of temperature. We have investigated spectral and lux-ampere
characteristics of photoconductivity and determined the mechanism of recombination
inherent to non-equilibrium current carriers. It has been ascertained that the capture of
electrons emitted by donor centers is caused by a strong electric field applied to a sample.
Keywords: single crystal, Ag3In5Se9, thermostimulated current, photoconductivity, lux-
ampere characteristic, recombination.
Manuscript received 07.02.06; accepted for publication 23.10.06.
1. Introduction
In the work [1], authors reported the existence of a new
class of ternary semiconductor compounds with the
general formula VI
9
III
5
I
3 CBA . The further researches
[2, 3] showed these compounds to be promissing in
manufacturing the photoconverters capable to work
under conditions of high temperatures as well as
increased frequencies of following electric pulses. In this
work, we give the results of photoelectric researches in
Ag3In5Se9.
2. Results and discussion
The spectrum of photoconductivity inherent to
Ag3In5Se9 was investigated in the samples grown by
methods of zone crystallization (a series of low-ohmic
samples – LO) and slow cooling (a series of high-ohmic
samples – HO), at a constant temperature gradient.
Conductivity of the samples and the mobility of current
carriers in them had the following values at the room
temperature:
1) for HO – ;cmOhm106.4 117 −−−⋅=σ
s)/(Vcm120 2 ⋅=μ ;
2) for LO – ;cmOhm103 115 −−−⋅=σ
s)./(Vcm40 2 ⋅=μ
Using the X-ray analysis, it was revealed that
Ag3In5Se9 single crystals have a hexagonal elementary
cell with lattice parameters а = 8.01 Å, с = 16.46 Å.
Studying the photoconductivity was carried out both in
stationary, and in non-stationary modes.
The typical spectra of photoconductivity
(normalized per unity quantum flux) LO- also HO-
samples are shown in Fig. 1. Curves 1 and 3 were taken
at 100 K, curve 2 – at 300 K. Beside it, curves 1 and 2
represents spectrum in a mode of modulated (82 Hz)
illumination of the sample.
Low-ohmic crystals are photosensitive within the
quantum energy range 1…1.8 eV, and high-ohmic
crystals, in comparison with low-ohmic, are
photosensitive in a wider area from the side of high
energy stimulating quantum. The spectrum of
photoconductivity in all these crystals begins with area
of impurity absorption that is located at the edge of
fundamental absorption (1…1.2 eV) and is overlapped
with it. At the same time, it is difficult to determine the
value of the forbidden band width gEΔ using the Moss
criterion, as the photocurrent created by intrinsic
absorption is sufficiently high. In all the obtained spectra
of various samples, the value of gEΔ coincides within
the limits of an allowable error of calculation and equals
at 300 K eV01.022.1 ±=Δ gE , and at 100 K
eV01.024.1 ±=Δ gE . At the quantum energy 1.30 eV
the photocurrent reaches its peak value and with
increasing the energy monotonously decreases. The third
characteristic area in the photoconductivity spectrum is
the area close to 1.41 eV where the photocurrent has
some bend. With further increasing the quantum energy,
the photocurrent decreases and in low-ohmic crystals it
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 25-28.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
26
1
2
10
5
3
20
4
а)
LO
b)
HO
21.5
Photon energy (eV)
1
1.0
3
2
15 Ph
ot
oc
ur
re
nt
, a
rb
. u
ni
ts
0.01 eV/mm
Fig. 1. Spectral dependence of the photocurrent for a low-
resistance (a) and high-resistance (b) crystals of Ag3In5Se9 at
100 K (curves 1, 3) and 300 K (curve 2).
→→
cE ||light .
1 30
50
Photon energy (eV)
10
1.2 1.8
2
1.5
Ph
ot
oc
ur
re
nt
, a
rb
. u
ni
ts
0.01 eV/mm
Fig. 2. Spectral dependence of the photocurrent for high-
resistance samples (curve 1) and low-resistance ones (curve 2)
of Ag3In5Se9 at 100 K and
→→
xE ||light ,
→→
zE || .
gradually tends to zero when reaching the quantum
energy 2 eV. However, here high-ohmic crystals behave
in another way. Since 1.5 eV (the fourth area of a
spectrum, Fig. 1b), the photocurrent grows and accepts
the maximal value at 1.8 eV at temperature 300 K and
1.87 eV at 100 K. As it is shown, this maximum is
approximately 0.07 eV shifted to the side of smaller
energies with the growth of the sample temperature from
100 up to 300 K.
It is necessary to note that the maximum or bends
in the photoconductivity spectrum at the quantum
energies exceeding gEΔ are also found in single
crystals of AgInSe2. In the work [2], it is explained with
the fact that the spin-orbital splitting takes place in the
valence band of AgInSe2, which is conditioned by the
mixing the Ag 4d-levels with р-levels of other atoms. By
this time, there formed three valence subbands. The
lowest interband transitions from these A, B and C
subbands are equal 1.24, 1.34, and 1.6 eV, respectively.
Probably, the same occurs in Ag3In5Se9 compounds. In
comparison with AgInSe2, the relative number of Ag
atoms in the formula unit of Ag3In5Se9 is less. In the
photoconductivity spectrum of crystals Ag3In5Se9,
photocurrent maxima corresponds to the quantum
energies 1.30, 1.41, and 1.80 eV.
As seen, they strongly differ from the
corresponding values of AgInSe2. In the work [2], it is
also shown, that the photoconductivity spectrum shape
strongly changes when turning the polarization vector of
incident light around the normal to the surface of a
sample. The amplitude of the found peaks depends on
the light polarization. It is revealed by us that the
spectrum of photoconductivity also depends on the
direction of the applied electric field. Fig. 2 shows
photoconductivity of high- and low-ohmic samples
(curves 1 and 2, respectively) at 100 K. The electric field
→
E is directed along the axis
→
z (in parallel to a crystal
axis
→
c ), and the light beam falls in parallel to axis
→
x .
The spectrum differed from the spectra shown in Fig. 1,
in range of quantum energies exceeding 1.5 eV. At
→→
zE || in the area above 1.5 eV in the high-ohmic
samples, the photocurrent has small increase, and then
starting from 1.6 eV remains constant. Some bend near
1.53 eV is also inherent to some low-resistance samples.
This characteristic part occupies a maximum in the
interval 1.5…1.95 eV at
→→
⊥ zE . Photosensivity of low-
and high-ohmic samples in conditions
→→
zE || and
→→
⊥ xE light in the specified interval of incident quantum
energies when light is non-polarized can be accepted as
a constant (independent from hν). It is necessary to note
that all the abovementioned spectra of photoconductivity
were measured inside the part of current-voltage
characteristics (CVC) where the Ohm law is valid. The
electric field strength is the same in all the parts of a
spectrum and equals 10 V/cm. But CVC of high-ohmic
samples obeys the Ohm law only up to 180 V/cm, the
nonlinear part is further observed. For comparison in
Fig. 3, we show the spectra of photoconductivity for
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 25-28.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
27
40
1.0
2
1.5
60
2.0
1
20 Ph
ot
oc
ur
re
nt
, a
rb
. u
ni
ts
Photon energy (eV)
0.01 eV/mm
Fig. 3. Spectrum of the photocurrent of the high-resistance
sample of Ag3In5Se9 at strong (Е = 350 V/cm, curve 1) and
weak (Е = 10 V/cm, curve 2) fields and
→→
⊥ zE light ,
→→
xE || .
μA
I F
F, arb. units
100 300
100
200
1
2
Fig. 4. Lux-ampere characteristics of the high-resistance
(curve 1) and low-resistance (curve 2) Ag3In5Se9 at 300 K.
high-ohmic crystals at 100 K,
→→
⊥ zE light , at strong (Е =
350 V/cm, curve 1) and weak (Е = 10 V/cm, curve 2)
fields. Spectra were measured in the mode of constant
illumination of samples, the intensity of illumination in
both spectra was identical.
Photosensivity of the sample at Е = 350 V/cm
begins with the energy of the incident quantum close to
0.95 eV. However, the spectrum 2 begins with the lower
energy. Therefore, it is possible to tell that there is an
electric decay of impurity photoconductivity. As it is
clear from the figure, the photocurrent corresponding to
the certain value of quantum, in the spectrum 1 is less
than in the spectrum 2 within the interval 0.95…1.7 eV.
It is probably connected with reduction of the carrier
mobility in strong electric fields (such a dependence
takes place in dark electroconductivity). In the spectrum
1, in the area around the first maximum of the
photocurrent, there is a breakage. Here one can observe
current instability, i.e., aperiodic oscillations of the
photocurrent. The amplitude of the second photocurrent
peak grows with the growth of the electric field, the peak
is formed. It is possible to assume, that it is associated
with the influence of strong electric field on defect
surface states.
Shown in Fig. 4 are lux-ampere characteristics
(LAC) of low- and high-ohmic samples in weak electric
fields at Т = 300 K. The wavelength of incident light
corresponded to the peak value of the photocurrent in the
spectrum of photoconductivity. The straight line 1
expresses LAC of the high-ohmic samples. Presence and
extent of various parts on LAC is usually determined by
initial electron filling the r-centers [3]. With the growth
of a filling degree the linear part of LAC gradually
“supersedes” both the sublinear and saturation ones, as
the r-centers are strongly exhausted as a result of
recharging the centers already at rather weak excitation.
Linear recombination observable in Ag3In5Se9 at 300 К,
confirms that in the given interval of intensities (I)
electron and hole filling the r-centers remains practically
constant, hence, nτ does not depend on I. Curve 2 in the
figure expresses LAC of low-resistance samples. It
consists of two linear parts and a transitive sublinear
part. Such course of LAC, probably, can be associated
with capture of a hole with r-centers up to the small
limited concentration corresponding to the inflection
point.
The character of LAC for low- and high-ohmic
samples at 100 K is identical. And LAC obeys the law of
quadratic bimolecular recombination. It means that the
mechanisms of recombination in both cases are the
same.
Presence of a long-term relaxation of photo-
conductivity testifies to existence in crystals of levels of
sticking, which were investigated by measurement of
temperature dependence of thermo-stimulated current
(TSC). The non-equilibrium carriers created at the
preliminary excitation with the quantum of the energy
eV22.1=νh , can be not captured only by repulsive
centers. However, as it is known [4], the centers start to
capture electrons at rather low
→
E (about 10 V/cm).
When this condition is satisfied in our experiments,
levels of sticking have not been found. Therefore, at
preliminary excitations it was necessary to increase the
applied electric field gradually. Starting from 40 V/cm,
the curve ( )Tσ shows the TSC peak. With the further
increase in the electric field Eexc, in the course of
preliminary excitation, the level of filling the traps began
to grow. The family of TSC curves at various fields of
excitation is shown in Fig. 5. With increase of Eexc up to
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 25-28.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
28
7
µA
T, K
I T
SC
9
8
50
6
5
4
3 2
1
150 250200
25
75
Fig. 5. ТSС curve for Ag3In5Se9 at various fields after
preliminary excitation; Е equals: 40 V/cm (1), 70 (2), 120 (3),
180 (4), 240 (5), 320 (6), 500 (7), 700 (8), 1000 (9).
180 V/cm, the temperature ( )mT corresponding to
maximum TSC grows, the further increase of Eexc up to
350 V/cm practically does not change mT , but above
350 V/cm with the growing Eexc, on the contrary, mT
decreases. Similar influence of an electric field on levels
of sticking was revealed in the work [5]. Authors
concluded that with the growth of the voltage, the TSC
peak corresponds to a deeper Fermi quasi-level for traps.
The same occurs, probably, in this case. Depth of
deposition of a level of the sticking, found of the
analysis of TSC curves, is equal to eV12.0=tE .
With the purpose to ascertain the mechanism of
TSC recombination, we investigated the dependence of
mT on time of excitation at the fixed values of Eexc. It
appeared that mT does not depend on the excitation
time. Hence, the found level of sticking is slow.
For the maximal value of the capture cross-section,
we obtained 219 cm105.2 −⋅=S . Thus, the level of
sticking observed by us is repulsive.
The research of the absorption spectra at various
temperatures has shown that the edge of intrinsic
absorption is formed by direct interband transitions. The
obtained values of the forbidden gap, its temperature
coefficient completely coincide with the results of
photoelectric researches.
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F.M. Aliev, G.G. Huseynov, New class of ternary
semiconductor compounds of VI
9
III
5
I
3 CBA type //
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2. V.I. Tahirov, H.A. Huseynov, M.B. Djafarov,
Stimulation of low-frequency oscillation of current
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New class of ternary semiconductor compounds of
VI
9
III
5
I
3 CBA type. Baku State University, Baku,
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conductors. Naukova dumka, Kiev, 1981, p. 248
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Recombination of hot electrons by repulsive
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