Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K
Ge₁₋xSix solid solutions are one of promissing materials for semiconductor technique. However, their electrical and optical properties, especially with silicon content more than 5 at. % have been little studied. In particular, in the number of works [1-3] there have been presented the experimental r...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2006
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K / Sh.M. Abbasov, Y.T. Agaverdiyeva, T.I. Kerimova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 22-24. — Бібліогр.: 10 назв. — англ. |
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irk-123456789-1216132017-06-16T03:03:59Z Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K Abbasov, Sh.M. Agaverdiyeva, Y.T. Kerimova, T.I. Ge₁₋xSix solid solutions are one of promissing materials for semiconductor technique. However, their electrical and optical properties, especially with silicon content more than 5 at. % have been little studied. In particular, in the number of works [1-3] there have been presented the experimental results of study in the region 0.52 eV in germanium irradiated by fast electrons, gamma-rays and protons at the temperature of liquid nitrogen. In the literature, however, there are no data on studying the absorption band in the range 0.52 eV in Ge₁₋xSix solid solution irradiated by fast electrons. 2006 Article Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K / Sh.M. Abbasov, Y.T. Agaverdiyeva, T.I. Kerimova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 22-24. — Бібліогр.: 10 назв. — англ. 1560-8034 PACS 42.25.Bs, 61.82.Fk http://dspace.nbuv.gov.ua/handle/123456789/121613 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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Ge₁₋xSix solid solutions are one of promissing materials for semiconductor technique. However, their electrical and optical properties, especially with silicon content more than 5 at. % have been little studied. In particular, in the number of works [1-3] there have been presented the experimental results of study in the region 0.52 eV in germanium irradiated by fast electrons, gamma-rays and protons at the temperature of liquid nitrogen. In the literature, however, there are no data on studying the absorption band in the range 0.52 eV in Ge₁₋xSix solid solution irradiated by fast electrons. |
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Article |
| author |
Abbasov, Sh.M. Agaverdiyeva, Y.T. Kerimova, T.I. |
| spellingShingle |
Abbasov, Sh.M. Agaverdiyeva, Y.T. Kerimova, T.I. Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Abbasov, Sh.M. Agaverdiyeva, Y.T. Kerimova, T.I. |
| author_sort |
Abbasov, Sh.M. |
| title |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K |
| title_short |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K |
| title_full |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K |
| title_fullStr |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K |
| title_full_unstemmed |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K |
| title_sort |
study of the absorption band in the range 0.3-0.9 ev inherent to solid solutions p-ge₁₋xsix irradiated by fast electrons at the temperature 77 k |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2006 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/121613 |
| citation_txt |
Study of the absorption band in the range 0.3-0.9 eV inherent to solid solutions p-Ge₁₋xSix irradiated by fast electrons at the temperature 77 K / Sh.M. Abbasov, Y.T. Agaverdiyeva, T.I. Kerimova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2006. — Т. 9, № 3. — С. 22-24. — Бібліогр.: 10 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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2025-07-08T20:13:26Z |
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2025-07-08T20:13:26Z |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 22-24.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
22
PACS 42.25.Bs, 61.82.Fk
Study of the absorption band in the range 0.3-0.9 eV
inherent to solid solutions p-Ge1−xSix irradiated
by fast electrons at the temperature 77 K
Sh.M. Abbasov, Y.T. Agaverdiyeva, T.I. Kerimova
Institute of Radiation Problems, Azerbaijan NAS
Phone: (+99412) 393-391; fax: (+99412) 398-318
E-mail: sh_abbasov@rambler.ru
Abstract. Ge1−xSix solid solutions are one of promissing materials for semiconductor
technique. However, their electrical and optical properties, especially with silicon content
more than 5 at. % have been little studied. In particular, in the number of works [1-3]
there have been presented the experimental results of study in the region 0.52 eV in
germanium irradiated by fast electrons, gamma-rays and protons at the temperature of
liquid nitrogen. In the literature, however, there are no data on studying the absorption
band in the range 0.52 eV in Ge1−xSix solid solution irradiated by fast electrons.
Keywords: germanium-silicon alloy, optical absorption, energy of electrons, divacancy.
Manuscript received 08.02.06; accepted for publication 23.10.06.
1. Introduction
In a series of works [1, 4], there have been presented the
experimental results of studying the absorption band of
germanium and n-Ge1−xSix solid solutions irradiated by
fast electrons, gamma rays and protons at the
temperature of liquid nitrogen in the range of 0.3 to
0.9 eV. However, in the literature, there are no data on
study of the absorption band in the same range for p-
Ge1−xSix solid solutions irradiated by fast electrons.
2. Experimental
This work presents the results of measurements of IR
absorption spectra, impurity photoconductivity and Hall
effect in the samples of p-type Ge1−xSix solid solution,
alloyed by gallium with the specific resistances of 0.3 to
1.0 Ohm⋅cm irradiated at 77 K by electrons with the
energy 4.5 MeV up to the integral fluxes 2·1017 cm2.
Irradiation was effected by the procedure described in [2].
The samples of germanium and Ge1−xSix solid
solution of n-type with 5, 10, and 15 at. % Si were
grown by the Czochralski method with additional
feeding.
The thickness of samples was 0.8…1.0 mm, which
allowed to obtain the uniform by depth distribution of
radiation defects by using electrons with the energy
mentioned above.
3. Results and discussion
There were studied the radiation defects responsible for
absorption in the region 0.3…0.9 eV in p-Ge1−xSix and
Ge solid solutions alloyed Ga irradiated by fast electrons
with the energy 4.5 MeV at the temperature of liquid
nitrogen. The irradiation was performed by electrons to
the integral fluxes Ф = 2.5⋅1017 cm−2.
The results of the IR-absorption and Hall
coefficient measurements on the samples with the
concentration 2.5·1017 cm−3 showed that absorption in
the range 0.3-0.9 eV is detected independently of the
initial impurity concentration (though the basic carrier
concentration at such irradiation slightly changes). But
it should be noted that at given dosage and energy of
electrons, the increase of the initial carrier
concentration results in the increase of the absorption
band intensity.
Shown in the figure is the change of the absorption
band before and after irradiation by electrons. In the
germanium samples, the change is displayed for the flux
Ф = 3.5·1016 cm−2 and in the p-Ge1−xSix samples with 5,
10 at.% Si – at the flux 2.5⋅1016 cm−2. In samples with
x = 0.15, the band was not observed though with
increasing Si content the irradiation dosage increases
necessary for appearance of absorption band. With
increasing the silicon content in solid solution, a band
shifts toward shorter waves.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 22-24.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
23
Spectra of absorption of p-Ge1−xSix samples before (1-4) and
after (1´-4´) irradiation by electrons with the energy 4.5 MeV.
Ф = 5⋅1016 cm−2 (1) and 2⋅1017 cm−2 (2-4), when x = 0 (1);
0.05 (2); 0.10 (3) and 0.15 (4).
Studies of the Hall effect on Ge and p-Ge1−xSix
samples with the concentration up to 5⋅1016 cm−3 showed
that after irradiation in the germanium sample there is a
level with the energy state Ev+0.16 eV and, in the p-
Ge1−xSix sample with x = 0.05, we have Ev+0.18 eV, with
x = 0.10 − Ev+0.22 eV, with x = 0.15 no levels appear.
The obtained results show that the energy levels of
radiation defects in the samples of p-type Ge1−xSix solid
solution differ from these in the samples of n-type.
These energy levels in spectra of IR-absorption give
bands with the peaks 0.52, 0.55, and 0.59 eV,
respectively.
From these results one can conclude that the
spectrum of radiation defects strongly depends on the
silicon content and the type of conductivity of Ge1−xSix
solid solution.
Before and after irradiation as well as after each
annealing within the temperature range of 77 to 420 K,
the concentrations of current carriers and specific
conductivity were measured at the temperature of liquid
nitrogen in darkness.
The decrease in the concentration of current carriers
within the temperature range of 8 to 160 K is difficult to
be explained by electron adherence. In this case, the
adherence centre should be attributed the extremely small
cross-sections for capture of holes. At this stage, crystal
properties change under action of illumination. As a result
of irradiation, the metastable formations seem to arise
capable to be rebuilt when heating and illuminating.
Possibility for defect rebuilding when heating was
mentioned previously [1, 3].
In n-type germanium, the vacancy motion was
observed at the temperature 70 K. If the analogy with
silicon is true then, in germanium of p-type, vacancies
will be mobile at the temperatures substantially above
77 K. Therefore, one can assume that, as a result of
metastable formation decay, free vacancies appear,
which take part in creation of more stable complexes. If
it is the case, then the activation energy (0.65 eV) at
160…260 K is due to the motion of free vacancies in
p-type germanium.
The order of-reaction at this stage and partial
reduction of hole concentration on exposing to white
light don’t contradict it. At 360…420 K practically the
full reduction of hole concentration occurs. The large
value of the activation energy (2.5 eV) and complex
mode of reaction show that, at this stage of annealing
process, the gallium impurity plays a significant role. In
[3, 4], there has been indicated that the activation energy
within the temperature range of 360 to 420 K depends on
the kind of alloying components, which indirectly
confirms the correctness of the assumption made.
In the samples of p-type as in those of n-type after
irradiation at the temperature of liquid nitrogen a light
sensitivity effect is observed.
Annealing of Ge1−xSix samples showed that with
increasing Si and the initial alloying component content
the temperature when annealing defects occurred
decreased.
In germanium samples after heating at the
temperature 235 K, the absorption band in the range
0.3…0.9 eV fully disappears at 175 K.
As it was already mentioned, there was no common
opinion concerning the structure of complex of radiation
holes responsible for absorption bands in the range
0.3…0.9 eV. In [5], radiation defects that give the
beginning of the absorption band have been identified
with a divacancy. In this work, the results are based on the
analogy between Ge and Si, in which divacancy have
been studied by EPR method. In [6], this assumption is
rejected showing that the defect is not an isolated vacancy
but is rather simple complex capturing the Frenkel pairs.
In [2], it was assumed that the defect under study is
a complex without donor atoms comprised, at least, two
components including more than one vacancy and
absorbed light only at certain charge states.
It is clear that the presented experimental data don’t
allow to elucidate the nature of given complex.
Considering the analogy between silicon and germanium
and eventually bearing in mind the coincidence of basic
properties of Ge and Ge1−xSix with x = 0.05…0.15 we
made an attempts to explain the structure of this defect.
In [7, 8], there have been carried out various
investigations of irradiated Si including the methods of
EPR, photoconductivity and IR-absorption, on the basis
of which there has been created a model of radiation
defect responsible for absorption bands 1.8, 3.3, and
3.9 μm in the spectrum of IR-absorption of Si. These
bands appear as a result of absorption in divacancy that
may be in various charge states. It has been shown in
these works that the absorption zone at 1.8 μm is due to
electron transition that is possible only in divacancy at
neutral or single-charge negative state whereas the
absorption zone 3.9 μm appears only at single-charge
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2006. V. 9, N 3. P. 22-24.
© 2006, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
24
negative state. Considering all above mentioned facts
and the results of the previous electrophysical and
optical investigations of defects at various charge states
(1, 4) and assuming that many crystallographic and
electrophysical parameters of Ge and Ge1−xSix with x =
0.05…0.15 are similar, we suppose that it is divacancies
that are responsible for the absorption band in the range
of 0.3 to 0.9 eV. As a zone was observed in n-Ge1−xSix
samples only after pn → conversion as a result of
irradiation [10] the most likely that divacancy might be
only at two charge states: neutral or single-charge
negative. As is shown above similarly to silicon in p-
Ge1−xSix when divacancy is at neutral state the
absorption band appears in the range 0.3…0.9 eV.
4. Conclusions
Following the authors of [2, 4], we draw conclusion that
the absorption band in the irradiated Ge1−xSix samples in
appropriate spectral region is related not with
photoelectrical active transitions but with vibration
levels of complex radiation defect, in this case the
adsorption displays when defect is at charge state which
is determined by Fermi level location. The defect
responsible for absorption either is not created as long as
the Fermi level is in the forbidden band, or it is created
and accumulated from the very beginning of irradiation
but displays only at the certain charge state.
In conclusion the authors consider it as their plea-
sant duty to express sincere gratitude to D.B. Gerasimov
for his help in performing experiments.
References
1. A.R. Basman, A.B. Gerasimov, M.K. Gogotishvili,
N.D. Dolidze, N.G. Kakhudze, B.M. Kovalenko,
Effect of donor impurities on kinetics of radiation
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