Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta
The influence of γ-quanta irradiation on photoelectrical and optical properties of lamellar GaS single crystals at different temperatures has been investigated. It is determined that the irradiation of pure crystals at the radiation dose equal to 30 krad results in the creation of shallow compensati...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2006
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| Цитувати: | Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta / R.S. Madatov, B.G. Tagiyev, A.I. Najafov, T.B. Tagiyev, I.A. Gabulov, Sh.P. Shakili // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 8-11. — Бібліогр.: 12 назв. — англ. |
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irk-123456789-1214422017-06-15T03:04:58Z Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta Madatov, R.S. Tagiyev, B.G. Najafov, A.I. Tagiyev, T.B. Gabulov, I.A. Shakili, Sh.P. The influence of γ-quanta irradiation on photoelectrical and optical properties of lamellar GaS single crystals at different temperatures has been investigated. It is determined that the irradiation of pure crystals at the radiation dose equal to 30 krad results in the creation of shallow compensative acceptors, which are photoactive recombination centers (r-centers), and as a result of this both the photosensitivity and a luminescence connected with r-centers are increased. Irradiation with a radiation dose more than 100 krad results in the quenching of both photosensitivity and recombination luminescence due to formation of complexes [VGa VS]. It is proposed that radiative recombination centers arising in the course of irradiation is conditioned by sulfur hole and interstitial gallium atoms. 2006 Article Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta / R.S. Madatov, B.G. Tagiyev, A.I. Najafov, T.B. Tagiyev, I.A. Gabulov, Sh.P. Shakili // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 8-11. — Бібліогр.: 12 назв. — англ. 1560-8034 PACS 61.82.Fk, 71.55.-i, 78.55.-m http://dspace.nbuv.gov.ua/handle/123456789/121442 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The influence of γ-quanta irradiation on photoelectrical and optical properties of lamellar GaS single crystals at different temperatures has been investigated. It is determined that the irradiation of pure crystals at the radiation dose equal to 30 krad results in the creation of shallow compensative acceptors, which are photoactive recombination centers (r-centers), and as a result of this both the photosensitivity and a luminescence connected with r-centers are increased. Irradiation with a radiation dose more than 100 krad results in the quenching of both photosensitivity and recombination luminescence due to formation of complexes [VGa VS]. It is proposed that radiative recombination centers arising in the course of irradiation is conditioned by sulfur hole and interstitial gallium atoms. |
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Article |
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Madatov, R.S. Tagiyev, B.G. Najafov, A.I. Tagiyev, T.B. Gabulov, I.A. Shakili, Sh.P. |
| spellingShingle |
Madatov, R.S. Tagiyev, B.G. Najafov, A.I. Tagiyev, T.B. Gabulov, I.A. Shakili, Sh.P. Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Madatov, R.S. Tagiyev, B.G. Najafov, A.I. Tagiyev, T.B. Gabulov, I.A. Shakili, Sh.P. |
| author_sort |
Madatov, R.S. |
| title |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
| title_short |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
| title_full |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
| title_fullStr |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
| title_full_unstemmed |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
| title_sort |
optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2006 |
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http://dspace.nbuv.gov.ua/handle/123456789/121442 |
| citation_txt |
Optical and photoelectrical properties of lamellar gallium sulfide single crystals irradiated by γ-quanta / R.S. Madatov, B.G. Tagiyev, A.I. Najafov, T.B. Tagiyev, I.A. Gabulov, Sh.P. Shakili // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 2. — С. 8-11. — Бібліогр.: 12 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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2025-07-08T19:54:28Z |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 8-11.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
8
PACS 61.82.Fk, 71.55.-i, 78.55.-m
Optical and photoelectrical properties of lamellar
gallium sulfide single crystals irradiated by γ-quanta
R.S. Madatov, B.G. Tagiyev, A.I. Najafov, T.B. Tagiyev, I.A. Gabulov, Sh.P. Shakili
Institute of Radiation Problems of Azerbaijan National Academy of Sciences
9, F. Agayev str., Baku, AZ 1143, tel./fax: (99412) 4398318
Abstract. The influence of γ-quanta irradiation on photoelectrical and optical properties
of lamellar GaS single crystals at different temperatures has been investigated. It is
determined that the irradiation of pure crystals at the radiation dose equal to 30 krad
results in the creation of shallow compensative acceptors, which are photoactive
recombination centers (r-centers), and as a result of this both the photosensitivity and a
luminescence connected with r-centers are increased. Irradiation with a radiation dose
more than 100 krad results in the quenching of both photosensitivity and recombination
luminescence due to formation of complexes [VGa VS]. It is proposed that radiative
recombination centers arising in the course of irradiation is conditioned by sulfur hole
and interstitial gallium atoms.
Keywords: photoluminescence, photoconductivity, single crystal, exciton, intra-central
transition.
Manuscript received 27.01.06; accepted for publication 29.03.06.
1. Introduction
In accordance with [1-3] AIIIBIV compounds are
interested as promising materials to create
semiconductor detectors of elementary particles and hard
electromagnetic radiation. Increased interest to these
compounds is caused by circumstance that though their
strong defectiveness they have high photosensitivity in
visible, infrared, roentgen and gamma-ray spectral
ranges [3-9]. These preliminary data pointed at the
possible prospective using the lamellar semiconductor
compounds for the development of photoelectrical
devices, radiation sources and radiation detectors. In this
connection, the research of their photoelectrical
properties behavior at ionizing radiation is actual.
The research results of optical and photoelectrical
characteristics of lamellar GaS single crystals are
irradiated by gamma-quanta with the purpose of local
levels detection in the crystal forbidden-zone are given
in this paper.
Investigated p-GaS single crystals were grown
using the Bridgman method at the Institute of Radiation
Problems of Azerbaijan National Academy of Sciences.
Sulfur surplus (1.5 %) is used during growth of single
crystals with the purpose to determine the hole filling
possibility by sulfur atoms. It was experimentally
determined that effective filling of holes occur at
annealing temperatures 500 to 700 °C. Specific
resistances of the samples along and perpendicularly to c
axis at the room temperature are 2·10 and
3·107 Ohm·cm, respectively. Indium was used as a
material for ohmic contacts. Indium was fused into GaS
surface at 150 °C. Irradiation of the samples by gamma-
quanta with energy 1.3 MeV was carried out using Co60
at 300 K. The crystals were cooled by liquid nitrogen
vapor during irradiation and, as a result, the temperature
of crystals was not higher than 290 K.
2. Experimental results
The investigations of photoconductivity and
photoluminescence in the range of wavelengths
0.4...1.0 µm at the temperatures 120 and 300 K have
been carried out to reveal local levels in the obtained
GaS single crystals.
Spectral dependences of photoconductivity for
obtained GaS single crystals are presented in Fig. 1. It is
necessary to note that initial GaS samples have
photoconductivity maxima near the fundamental
absorption edge at λ = 0.51 µm. In addition, observed are
intensive impurity peaks with maxima at λ = 0.61 µm
and λ = 0.70 µm (Fig. 1, curve 1). These maxima
correspond to the optical transition from the acceptor
level to the conduction band. Activation energy of the
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 8-11.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
9
Fig. 1. Spectral distribution of photoconductivity for GaS
single crystals: 1, 2 – without irradiation; 3, 4 – irradiated by
gamma-quanta (30 krad); 1, 3 at 300 K; 2, 4 at 120 K.
Fig. 2. Temperature dependences of photocurrent (λmax =
= 0.51 µm) for single crystals GaS: 1 – before irradiation; 2 –
30 krad; 3 – 100 krad.
levels is equal to 0.50 and 0.74 eV, respectively. It
coincides with the values given in [3, 4]. Photocurrent
increases approximately by 30-40 % after irradiation of
the samples by gamma-quanta with the dose equal to
30 krad. In this case, the maximum intensity at 0.61 µm
decreases and with increasing irradiation dose gradually
decrease and disappear at the dose equal to 100 krad
(Fig. 1, curves 2–4). The peak in the vicinity of 0.74 eV
is displaced to the short waves and appeared at
λ = 0.82 µm. It is seen from Fig. 1 that further irradiation
decreases the photoconductivity of GaS in all the
investigated spectral region (curves 3, 4). It is indicative
of generation of a high concentration of recombination
centers with the large capture cross-section for electrons.
The temperature dependences of photocurrent in
the initial and irradiated GaS samples at λ = 0.51 µm are
given in Fig. 2. The samples are irradiated by gamma-
quanta with the doses equal to 30 and 100 krad. As it is
seen, the irradiation does not influence on the
temperature dependence of photocurrent in GaS
samples. It is observed temperature quenching of
photocurrent at the temperature higher than 170 K. Such
sensitivity changes connected mainly with
rearrangement of intrinsic defect levels in the forbidden
zone and changing in hole filling ratio of sensitivity
centers in GaS. Photoluminescence spectra of the
investigated samples at 77 K are given in Fig. 3. Helium-
cadmium laser (λ = 0.3716 µm) was used for excitation.
Intensive exciton emission bands with λ1 = 0.48 µm are
observed in both GaS crystals irradiated by low doses
and unirradiated samples. The wide structureless band
having peaks of the considerable intensity located at
λ1 = 0.48 µm, λ2 = 0.52 µm and λ3 = 0.66 µm raised after
irradiation of samples with 30 krad dose. The observed
peak λ3 = 0.66 µm disappears at high irradiation doses
(curve 3, 100 krad), and the dependence behavior gets its
initial look similar to that before irradiation. The
dependence of the irradiation intensity and photo-
sensitivity on the irradiation dose is shown in Fig. 4. It is
seen that at low irradiation doses up to 30 krad, it is
observed heightened intensity band, and further
increasing the irradiation dose results in the decreased
intensity. The photoconductivity dependence of
irradiated samples demonstrates the same behavior.
3. Discussion of the obtained results
The researches of stationary characteristics of
photoconductivity and photoluminescence allow to
determine a recombination model in GaS single crystals
including post-gamma-irradiation influence. The
observation of such phenomena as radiation and
photoluminescence of the crystals as well as thermal
quenchering of photocurrent can be explained within the
framework of three-level recombination diagram
containing low – r, fast – s and capture levels – t for
majority charge carriers. It is known [11] that in the
thermodynamical state of equilibrium for
implementation of high photoconductivity the levels of r
and s should be completely filled by the holes. In this
case, the electron concentration Nr0 should correspond to
the following conditions:
0rN << ,, 00 rsrr NNNP <<=
where Nr and Pr0, Ns are the concentrations of r and s
centers, respectively. Majority charge carriers for GaS
are holes, and the condition Na > Nd is carried out.
Illuminating of the samples leads to the optical
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 8-11.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
10
Fig. 3. Photoluminescent spectra of GaS single crystals: 1 –
before irradiation; 2 – 30 krad; 3 – 100 krad.
Fig. 4. Photosensitivity dose dependences (1) and the
intensity of photoluminescence (2-4) for GaS single crystals :
λ = 0.48 µm (2); 0.53 (3); 0.66 (4).
recharging of local levels and, as a result, the filling of
these levels significantly differs from its dark value.
The complex researches at different temperatures
were carried out in order to determine the cause of
photoconductivity changing in the irradiated p-type GaS
samples. It is ascertained that at low irradiation doses
(up to 20 krad) the photosensitivity in the range of
intrinsic photoconductivity and the intensity of bands
with the peaks located at λf = 0.62 µm (Fig. 1, curve 2)
and λI = 0.48 µm (Fig. 3, curve 1) are not practically
changed, and it is an evidence of low speed
photosensitivity of the injected radiation defects. An
increase in photosensitivity for λmax = 0.51 µm and
decrease for λf = 0.62 µm occur with increasing gamma-
irradiation dose up to 30 krad. This fact is explained by
the increase of low recombination centers in the
composition where VS is included, and the decreasing
VGa concentration. On the basis of the obtained results, it
is difficult to give a conclusion about the nature of r-
centers, but it is possible to suppose that complex defects
with sulfur and gallium vacancies are responsible for
these centers. In fact, the decrease of the impurity peak
(0.62 µm) testifies to the decrease of the VGa
concentration, it seems due to interaction with Gai [5].
The researches results of photoluminescent spectra for
irradiated GaS crystals (Fig. 3, curves 2, 3) showed the
creation of radiation defects. It is seen from Fig. 3 that in
the excitation spectrum of luminescence for the
irradiated sample (30 krad) additional high intensity
maxima with λ2 = 0.53 µm and λ3 = 0.66 µm are formed
in addition to the exciton band (λ1 = 0.48 µm). It is
necessary to note that shortwave peak with λ1 = 0.48 µm
is conditioned by radiative recombination of free
electrons and its energetic position coincides with that
for the exciton peak n = 1 in the absorption spectrum
[2, 6]. It is known [12] that the boundary energy of
electrons required for sulfur atoms to be displaced into
the interstitial site is two times less than the energy
required for gallium atoms to be displaced. Therefore,
we can suppose that the acceptor centers (interstitial
sulfur atoms Si) are responsible for the band at 0.53 µm.
In this case, radiation occurs at the recombination of free
electrons with holes that are captured by the acceptor
centers Si. The shift of the luminescence peak (0.53 µm)
to the shortwave side of the spectrum and the decrease of
its intensity with increasing irradiation dose (Fig. 3,
curve 3) can be explained by shielding action of charged
holes on the radiation centers, which are Gai [7] and
removal of Si to different sinks, which could be VS,
defect cluster, dislocations and etc. It is worth to note
that the complex with Gai
+ atoms is responsible for
luminescence band 0.66 µm. The decrease of the
luminescence band (0.66 µm) intensity in the irradiated
GaS crystals (100 krad) is connected with complex
dissociation, as a result of that Gai
+ atoms annihilate and
VGa are formed. It is seen from Fig. 2 (curve 1) that TGF
is observed in initial crystals at temperatures T > 200 K
due to the development of thermal generation of
electrons, which forms r-levels inside C-zone and their
further capture at s-levels. On temperature decreasing
below 200 K, the photocurrent decreases, which shows
the localization of holes at t-levels and corresponding
electrons at r-recombination levels. As a result of Nr = Nt
formation accordingly to [11], the decrease of both the
hole lifetime and photocurrent occurs. It is seen from
Fig. 2 (curves 2, 3) that the irradiation does not influence
on the behavior of the photocurrent temperature
dependence, and TGF is observed at temperatures above
240 K. It means that irradiation by gamma-quanta leads
to the radiation sensitization in the temperature range
above 170 K. Such change of sensitivity is connected
with the change of the hole filling degree of sensitivity
centers in GaS as well as GaSe and GaTe [10].
Irradiation by gamma-quanta creates shallow capture
levels with the ionization energy 0.23 eV. These levels
compensate deep levels. The parameters of sensitizing r-
centers of recombination and trapping were determined:
the values of the capture cross-section for electron and
hole are equal to Snr = 2·10-14 and Spr = 5·10–19 cm-2,
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 2. P. 8-11.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
11
respectively, the concentration of these centers is equal
to 2·10–14 cm-3, and the energy state of trapping levels for
holes is Evt = 0.23 and 0.40 eV and their concentration is
Nt = 7·1014 – 2·1015 cm-3. All of these facts show that
irradiation by gamma-quanta with low dose leads to the
formation of radiative recombination centers in which
the band of 0.53 µm is determined by donor center with
participation of S vacancy, and the band of 0.66 µm is
determined by interstitial Ga atoms. The irradiation by
high doses (above 100 krad) leads to the photosensitivity
quenching and recombination luminescence recom-
bination due to the formation of bivacancies [VGa, VS].
4. Conclusion
Thus, the irradiation by gamma-quanta of pure crystals
leads to the formation of shallow acceptor capture levels
with the energy 0.23 eV. These levels compensate deep
donors, which are sensitizing recombination centers (r-
centers). It leads to the increasing of photosensitivity and
strengthening luminescence that is connected with r-
centers. Obtained experimental results in the irradiated
GaS crystals are explained satisfactorily within the
existing model [11].
References
1. G.A. Akhundov, Ph. D. dissertation, Baku, 1967.
2. V.P. Mushinskiy, M.I. Karaman, Optical properties
of chalcogenide gallium and indium. Kishinev,
1973, p. 71.
3. O.Z. Alekperov, M.Z. Zarbaliyev // Izvestiya AN
SSSR, Neorganich. materialy 34, No 10, p. 1163-
1167 (1998) (in Russian).
4. G. Fischer, Speculation of the band structure of the
layer compounds GaS and GaSe // Helv. Phys. Soc.
Acta 36, No 3, p. 1313-1325 (1963).
5. O.Z.Alekperov, M.Z. Zarbaliyev // Izvestiya AN
SSSR, Neorganich. materialy 35, No 11, p. 1315-
1320 (1999) (in Russian).
6. H. Kamimara, K. Nakao, Band structure and optical
properties of semiconductioning layer compounds
GaS and GaSe // J. Phys. Soc. Jpn 24, No 6, p.
1313-1325 (1968).
7. G.B. Abdullayev, A.Z. Abbasova et al. // Fizika
tekhnika poluprovodnikov 15, No 6, p 1320-1325
(1981) (in Russian).
8. R.S. Madatov, T.B. Tagiyev, I.A. Kabulov,
T.M. Abbasova // Semiconductor Physics, Quantum
Electronics and Optoelectronics 6(3), p. 278-281
(2003).
9. T.B. Tagiyev, R.S. Madatov, T.M. Abbasova // Ibid.
5(3), p. 261-263 (2002).
10. Yu.P. Gnatenko, Z.D. Kovalyuk, P.A. Skubenko //
Ukr. Fiz. Zhurn. 27(6), p. 838-842 (1982) (in
Russian).
11. V.E. Lashkarev, A.V. Lyubcjenko, M.K. Sheykman,
Non-equilibrium processes in photoconductors.
Naukova Dumka, Kiev, 1981, p. 264 (in Russian).
12. V.V. Emtsev, T.B. Mashovets, Impurities and hole
defects in semiconductors. Radio i svyaz’, Moscow,
1981, p. 248 (in Russian).
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