p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy
(Ge₂)x(GaAs)₁₋x graded gap layers were grown using the method of liquid phase epitaxy on GaAs substrates. Investigated are distributions of chemical components along the thickness of the epitaxial layer. In accord to the scan patterns obtained in characteristic X-rays, the layers have a perfect stru...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2005
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| Cite this: | p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy / AUTHORS // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 4. — С. 33-34. — Бібліогр.: 2 назв. — англ. |
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Sapaev, B. Saidov, A.S. Sapaev, I.B. 2017-06-14T16:02:06Z 2017-06-14T16:02:06Z 2005 p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy / AUTHORS // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 4. — С. 33-34. — Бібліогр.: 2 назв. — англ. 1560-8034 PACS 68.55.Ac, 81.15.-z https://nasplib.isofts.kiev.ua/handle/123456789/121540 (Ge₂)x(GaAs)₁₋x graded gap layers were grown using the method of liquid phase epitaxy on GaAs substrates. Investigated are distributions of chemical components along the thickness of the epitaxial layer. In accord to the scan patterns obtained in characteristic X-rays, the layers have a perfect structure, and the component distributions both along the thickness and the interface are rather monotonous, macroscopic defects and metal inclusions are absent. In the epitaxial layers, we created p-n junctions by diffusion of Zn from a gas phase. We studied the possibilities of using the GaAs-(Ge₂)x(GaAs)₁−x structures as solar converters including the near infra-red region. In this case, the GaAs substrate serves as a filter for light quanta with the energy hν < EgGaAs. The conversion efficiency dependences on the gradient x and the p-n junction position inside the (Ge₂)x(GaAs)₁−x graded gap layer are also shown. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy Article published earlier |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy Sapaev, B. Saidov, A.S. Sapaev, I.B. |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy |
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p-n junctions obtained in (ge₂)x(gaas)₁₋x varizone solid solutions by liquid phase epitaxy |
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Sapaev, B. Saidov, A.S. Sapaev, I.B. |
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Sapaev, B. Saidov, A.S. Sapaev, I.B. |
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2005 |
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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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(Ge₂)x(GaAs)₁₋x graded gap layers were grown using the method of liquid phase epitaxy on GaAs substrates. Investigated are distributions of chemical components along the thickness of the epitaxial layer. In accord to the scan patterns obtained in characteristic X-rays, the layers have a perfect structure, and the component distributions both along the thickness and the interface are rather monotonous, macroscopic defects and metal inclusions are absent. In the epitaxial layers, we created p-n junctions by diffusion of Zn from a gas phase. We studied the possibilities of using the GaAs-(Ge₂)x(GaAs)₁−x structures as solar converters including the near infra-red region. In this case, the GaAs substrate serves as a filter for light quanta with the energy hν < EgGaAs. The conversion efficiency dependences on the gradient x and the p-n junction position inside the (Ge₂)x(GaAs)₁−x graded gap layer are also shown.
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1560-8034 |
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https://nasplib.isofts.kiev.ua/handle/123456789/121540 |
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p-n junctions obtained in (Ge₂)x(GaAs)₁₋x varizone solid solutions by liquid phase epitaxy / AUTHORS // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 4. — С. 33-34. — Бібліогр.: 2 назв. — англ. |
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2025-11-25T21:02:32Z |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 4. P. 33-34.
© 2005, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
33
Fig. 1. Scheme of the cascade solar cell based on
(Ge2)x(GaAs)1−x graded gap structure:
1 – n-GaAs-substrate, 2 – variable gap solid solution
n-(Ge2)x(GaAs), 3 – p-(Ge2)x(GaAs)1−x.
PACS 68.55.Ac, 81.15.-z
p-n junctions obtained in (Ge2)x(GaAs)1–x varizone
solid solutions by liquid phase epitaxy
B. Sapaev, A.S. Saidov, I.B. Sapaev
Physical and Technical Institute of Uzbek Academy of Sciences,
2b, G. Mavlanov str.,700084 Tashkent, Republic of Uzbekistan
E-mail: bayram@physic.uzsci.net
Abstract. (Ge2)x(GaAs)1−x graded gap layers were grown using the method of liquid
phase epitaxy on GaAs substrates. Investigated are distributions of chemical components
along the thickness of the epitaxial layer. In accord to the scan patterns obtained in
characteristic X-rays, the layers have a perfect structure, and the component distributions
both along the thickness and the interface are rather monotonous, macroscopic defects
and metal inclusions are absent. In the epitaxial layers, we created p-n junctions by
diffusion of Zn from a gas phase. We studied the possibilities of using the GaAs-
(Ge2)x(GaAs)1−x structures as solar converters including the near infra-red region. In this
case, the GaAs substrate serves as a filter for light quanta with the energy hν < EgGaAs.
The conversion efficiency dependences on the gradient x and the p-n junction position
inside the (Ge2)x(GaAs)1−x graded gap layer are also shown.
Keywords: liquid phase epitaxy, solid solution, p-n junction.
Manuscript received 15.07.05; accepted for publication 25.10.05.
Multilayer cascade solar cells are one of the promising
cells of modern photoenergetics due to their high
efficiencies. Current investigations on the subject are
directed to increasing the spectral range of sensitivity
and to finding the most suitable cascade elements. The
majority of authors [1, 2] used Ge as a bottom element
of the cascade, which results in widening the spectral
sensitivity to long-wave side of the solar radiation. In the
works [1, 2], the solid solutions were prepared by the gas
and molecular beam epitaxy methods. In this paper, we
report on the solid solutions made up by the liquid phase
epitaxy and the investigations of dependences of the
main output parameters of (Ge2)x(GaAs)1−x cascade solar
cells on the variability of the bandgap width. We
constructed the graded gap structures p-(Ge2)x(GaAs)1−x
– n-(Ge2)x(GaAs)1−x – n-GaAs, where x varies from 0
to 1 (Fig. 1).
The structure was grown by the 1iquid phase
epitaxy method in an isolated cassette from confined
volume of bismuth solutions in the pure hydrogen flow
with the dew point of 213 to 218 K, which was
controlled. 〈111〉 oriented n-GaAs plates with the dia-
meter of 20 mm, thickness of 350 to 400 μm were used
as substrates with pure Bi solvents. The p-n junction was
formed during the crystal growth of the autodoping
p-type layers and by diffusion of Zn from a gas phase.
To define the optimal position d of the p-n junction
in the graded gap of (Ge2)x(GaAs)1−x solid solutions, we
studied the dependence of short circuit current Jsc, open
circuit voltage Voc, spectral sensitivity and efficiency η
on the ratio of d to the net thickness of the variable gap
solution w. For this aim, several samples were prepared
with different positions of p-n junction in the layer. The
gap width of the layer was varied between
0.6 < Eg < 1.43 eV. Consequently, the peak of photo-
sensitivity (Fig. 2), short circuit current, and efficiency
were different for these layers.
In Fig. 3, the dependence of output power of the
samples on the parameter d is given. It increases with the
displacement of the p-n junction to the low bandgap
region. The power increase is not so high as was
expected.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 4. P. 33-34.
© 2005, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
34
Fig. 2. Spectral characteristics of the solar cells based on solid
solution (Ge2)x(GaAs)1−x with various p-n junction positions
d: 1 – 12…13, 2 − 7…8, 3 − 3…4 μm.
Fig. 3. Dependence of the output power for the solar cells
(Ge2)x(GaAs)1−x on the p-n junction position. Values of d are
the same as in Fig. 2.
Fig. 4. Open circuit voltage as a function of the p-n junction
position, d. Values of d are the same as in Fig. 2.
Fig. 5. Short circuit current of the variable gap
(Ge2)x(GaAs)1-x solar cells as a function of the relative p-n
junction position d/w. Values of d are the same as in Fig. 2.
Dependences of Jsc and Voc on d/w are presented in
Figs 4 and 5, respectively. The analysis show that the
short current increases from 3…4 to 15…17 mA/cm2 and
open circuit voltage from 0.67…0.72 to 0.21…0.25 V
with increasing d. Then the maximum efficiency value
can be obtained for d between 3 and 4 µm, which
corresponds to d/w between 0.23 and 0.26. The solar cell
performance considered (Figs 4 and 5) depends on the
area only quantitatively and not qualitatively. The
increase of Jsc with increasing d at its low values can be
explained as a decrease in the open circuit voltage and
efficiency. As it follows from Fig. 5, the open circuit
voltage decreases linearly with increasing the thickness
of the variable gap semiconductor.
Values of d are the same as in Fig. 2.
Our results have demonstrated that the variable gap
solid solutions (Ge2)x(GaAs)1−x can be succesfully used
for cascade solar cells as bottom elements. By varying
the thickness of the graded gap layer and by creating the
solar cells with an upper wide gap window on the
opposite of substrate, the efficiency of cascade cells can
be increased significantly.
The main problem in the technology of designing the
cascade cells is balancing the short circuit current of
cascade elements. The construction proposed in the
paper simplifies the problem significantly and can be
utilized successfully in further developments of the
similar cascade solar cells.
It is known that the cascade GaAs-Ge solar cells
must be spectral sensitive in the wide wavelength region
from 0.4 up to 1.7 µm of solar radiation. The values of
the photogenerated current in GaAs and Ge cells allow
to obtain high photovoltages with minimum losses even
at their series connection. The obtained results show that
the investigated cascade cells are effective and repro-
ducible as compared with the currently available data.
References
1. L.D. Partain, M.S. Kurula, R.E. Wiess et al., 26.1 %
solar cell efficiency for Ge mechanically stacked under
GaAs // J. Appl. Phys. 62, N 7, p. 3010-3015 (1987).
2. J.N. Bullock, C.H. Wu, J.F. Wise, Interface contribution
to GaAs/Ge heterojunction solar cell efficiency // IEEE
Trans. Electr. Devices 36, N 7, p. 1238-1243 (1989).
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