Photoelectrical characteristics of two-dimensional macroporous silicon structures
Photoelectrical properties of macroporous silicon structures were investigated in the near infrared spectral range (1 to 8 μm). Angular dependences of photoconductivity, its amplification, realization of the single-mode optical regime, essential domination of the absorption over the light reflection...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2004
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| Цитувати: | Photoelectrical characteristics of two-dimensional macroporous silicon structures / L.A. Karachevtseva, V.F. Onischenko, M.I. Karas’, O.I. Dandur’yants, F.F. Sizov, O.J. Stronska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 4. — С. 425-429. — Бібліогр.: 8 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1192272025-02-09T16:59:31Z Photoelectrical characteristics of two-dimensional macroporous silicon structures Karachevtseva, L.A. Onischenko, V.F. Karas, M.I. Dandur’yants, O.I. Sizov, F.F. Stronska, O.J. Photoelectrical properties of macroporous silicon structures were investigated in the near infrared spectral range (1 to 8 μm). Angular dependences of photoconductivity, its amplification, realization of the single-mode optical regime, essential domination of the absorption over the light reflection by structures of macroporous silicon are explained by formation of the plasmon type surface polaritons. Photoconductivity bands correlate with maxima of intrinsic and impurity light absorption. The change in the photoconductivity value is mainly determined by the growth of the electron mobility. 2004 Article Photoelectrical characteristics of two-dimensional macroporous silicon structures / L.A. Karachevtseva, V.F. Onischenko, M.I. Karas’, O.I. Dandur’yants, F.F. Sizov, O.J. Stronska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 4. — С. 425-429. — Бібліогр.: 8 назв. — англ. 1560-8034 PACS: 71.25.Rk, 81.60Cp https://nasplib.isofts.kiev.ua/handle/123456789/119227 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Photoelectrical properties of macroporous silicon structures were investigated in the near infrared spectral range (1 to 8 μm). Angular dependences of photoconductivity, its amplification, realization of the single-mode optical regime, essential domination of the absorption over the light reflection by structures of macroporous silicon are explained by formation of the plasmon type surface polaritons. Photoconductivity bands correlate with maxima of intrinsic and impurity light absorption. The change in the photoconductivity value is mainly determined by the growth of the electron mobility. |
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Article |
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Karachevtseva, L.A. Onischenko, V.F. Karas, M.I. Dandur’yants, O.I. Sizov, F.F. Stronska, O.J. |
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Karachevtseva, L.A. Onischenko, V.F. Karas, M.I. Dandur’yants, O.I. Sizov, F.F. Stronska, O.J. Photoelectrical characteristics of two-dimensional macroporous silicon structures Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Karachevtseva, L.A. Onischenko, V.F. Karas, M.I. Dandur’yants, O.I. Sizov, F.F. Stronska, O.J. |
| author_sort |
Karachevtseva, L.A. |
| title |
Photoelectrical characteristics of two-dimensional macroporous silicon structures |
| title_short |
Photoelectrical characteristics of two-dimensional macroporous silicon structures |
| title_full |
Photoelectrical characteristics of two-dimensional macroporous silicon structures |
| title_fullStr |
Photoelectrical characteristics of two-dimensional macroporous silicon structures |
| title_full_unstemmed |
Photoelectrical characteristics of two-dimensional macroporous silicon structures |
| title_sort |
photoelectrical characteristics of two-dimensional macroporous silicon structures |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2004 |
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https://nasplib.isofts.kiev.ua/handle/123456789/119227 |
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Photoelectrical characteristics of two-dimensional macroporous silicon structures / L.A. Karachevtseva, V.F. Onischenko, M.I. Karas’, O.I. Dandur’yants, F.F. Sizov, O.J. Stronska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 4. — С. 425-429. — Бібліогр.: 8 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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2025-11-28T05:11:00Z |
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2025-11-28T05:11:00Z |
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1850009628880928768 |
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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 4. P. 425-429.
© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
425
PACS: 71.25.Rk, 81.60Cp
Photoelectrical characteristics of two-dimensional
macroporous silicon structures
L.A. Karachevtseva, V.F. Onischenko, M.I. Karas’, O.I. Dandur’yants, F.F. Sizov, O.J. Stronska
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, prospect Nauky, 03028 Kyiv, Ukraine
Phone: 38 (044) 525-98-15. Fax: 38 (044) 525-83-42
E-mail: lakar@isp.kiev.ua; sizov@isp.kiev.ua; stronska@isp.kiev.ua
Abstract. Photoelectrical properties of macroporous silicon structures were investigated
in the near infrared spectral range (1 to 8 μm). Angular dependences of
photoconductivity, its amplification, realization of the single-mode optical regime,
essential domination of the absorption over the light reflection by structures of
macroporous silicon are explained by formation of the plasmon type surface polaritons.
Photoconductivity bands correlate with maxima of intrinsic and impurity light
absorption. The change in the photoconductivity value is mainly determined by the
growth of the electron mobility.
Keywords: macroporous silicon structures, optical transmittance, photoelectrical
characteristics.
Manuscript received 14.10.04; accepted for publication 16.12.04.
1. Introduction
The study of photonic crystals are a new direction of
solid-state physics that is rapidly progressing. These
crystals are periodic structures with periodic modulation
of permittivity where the photonic bands are formed by
analogy to electronic bands in crystals. The perspective
material for two-dimensional photonic structures is the
macroporous silicon obtained by a method of
photoanodic etching. It is promoted by low-cost
technology of electrochemical etching, possibility to
create structures with a necessary geometry, the high
ratio of the pore depth to the pore diameter. The
macroporous silicon structures are perspective for the
development of optical devices and sensors in the near
infrared spectral range due to the presence of intensive
absorption bands [1-3]. This paper concerns the results
of studying the photoelectrical properties of
macroporous silicon in near infrared spectral range
(1…8 μm). In particular, studied were the angular
dependences of photoconductivity, optical transmittance,
photoconductivity spectra, and relaxation time.
Dependences of electron conductivity, concentration and
mobility on the illumination intensity were also
researched.
2. Experiment
The initial samples were n-type silicon with (100)
orientation and 2 to 5 Ohm⋅cm conductivity. Macropores
of 1 to 15 μm diameter were formed due to generation
and transfer of nonequilibrium holes to the
electrochemically treated n-Si surface after the optical
band-to-band electron-hole generation [1, 2]. Initial n-Si
plates were chemically polished in 1:3 HF and HNO3
solutions and anisotropically etched in 10% solution of
KOH. An ohmic contact was fabricated by rubbing In-
Ga eutectic alloy around the circular area exposed to the
electrolyte. The samples were mounted in an
electrochemical cell and connected with the potentiostat
by the three-electrode scheme. The electrolyte was 5
weight % solution of hydrofluoric acid. The applied
voltage was measured in relation to a platinum wire near
the sample surface. During the electrochemical etching
process, the samples were illuminated by radiation of
100 W tungsten lamp. Periodic structures as well as
structures with arbitrary distribution of macropores have
been fabricated (Fig. 1).
Optical transmittance was measured using IR Fourier
spectrometer IFS-113, IR spectrophotometer, He-Ne laser
and Specord M85.
3. Results and discussion
The photoconductivity of macroporous silicon
structures was measured. It depends on the direction of
electromagnetic radiation (Fig. 2). There are maxima of
photoconductivity which are observed at the normal
incidence of electromagnetic radiation, at angles close to
the total internal reflection angle relatively to macropore
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 4. P. 425-429.
© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
426
Fig. 1. Microphotos of macroporous silicon structures with periodic and arbitrary distributed pores.
0 40 80
0
40
80
120
4
1
2
3
P
ho
to
co
nd
uc
tiv
ity
,a
rb
.u
n.
Incidance angle, degree
Fig. 2. Photoconductivity dependence of macroporous
silicon structures on the angle of incidence for the
electromagnetic radiation (λ = 0.94 μm) at the voltage (in
mV) on the sample without illumination: 1 – 3; 2 – 27; 3 –
55; 4 – 70 (Т = 77 К).
Fig. 4. Scheme of periodic macroporous silicon structure with
the pore radius rp and the radius of a silicon column rSi.
Fig. 3. Transmittance spectra of two macroporous silicon
structures.
Fig. 5. Photoconductivity spectral dependence of the
macroporous silicon structure.
x
yz
(01)
rp
a
rSi
(10)
500 400 3000 2000
5
10
15
Tr
an
sm
itt
an
ce
, %
Wavenumber, cm–1
2
1
1000
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 4. P. 425-429.
© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
427
800 1000 1200 1400 1600 1800
3
6
9
12
15
x10
4
5
1
2
3
P
ho
to
co
nd
uc
tiv
ity
, a
rb
.u
n.
Wavelenqth, nm
4 8 12 16 20
10-5
10-4
10-3
10-2
3
1
2
Li
fe
tim
e,
s
103/T, K-1
Fig. 6а. Photoconductivity spectral dependence for silicon
single crystal (5) and macroporous silicon structures in the
range of the intrinsic light absorption (1–4).
Fig. 7. Temperature dependences of the relaxation time of
photoconductivity for two samples of: macroporous (1, 2) and
monocrystalline (3) silicon.
10-3
10-2
10-1
1015101410131012
I1/5
I1/5
s ph
, a
rb
. u
ni
ts
Light intensity, quantum/(cm2s)
Fig. 6b. Photoconductivity signal maximum dependence
on the distance between macropores.
Fig. 8. Photoconductivity dependence on the illumination
intensity for macroporous silicon structures ( – 77 K, –
300 K).
walls, and at grazing light incidence relatively to the
structure surface. Such dependence of photoconductivity
is caused by the optical characteristics.
The optical transmittance coefficient of
macroporous silicon structures is more than that for the
homogeneous material by a factor of 102 in the range of
wavelengths smaller than the optical period of
macroporous structure (Fig. 3). Absorption coefficient is
in the range from 300 to 500 cm–1. Absorption peaks and
steps are observed in the spectrum of impurity
absorption. In the longwave region of the spectrum, the
step frequency is proportional to the distance between
macropores and, in the shortwave region, it is
proportional to the diameter of macropores. In the
previous publication [3], it was shown that, on
macroporous silicon structure, the optical modes are
formed on silicon columns in longwave region and on
the macropores in the shortwave one (Fig. 4). So, the
photoconductivity has been measured in this spectral
range, where the directed optical modes are formed on
macropores.
The transmission spectra of macroporous silicon
structures were measured by a spectrophotometer with the
aperture of about 10°, therefore, at the formation of the
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 4. P. 425-429.
© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
428
optical mode, the multimode regime should be realized.
However, the step formation testifies to realization of the
single mode regime, which is caused by the surface
oscillator fluctuations on a macropore surface and surface
polariton formation. This is supported by the preferable
absorption of the р-components of the incident
electromagnetic radiation by macroporous silicon
structures. Besides, we measured the reduction in the
intensity of reflected light and increase in the absorption.
It is an additional feature of exciting the surface
electromagnetic waves [4, 5].
In other words, at the normal light incidence, the
directed optical modes are formed by macropores.
Surface waves are formed in the region of the angle of
total internal reflection respectively to macropore walls.
At grazing incidence, the surface diffraction that is
caused by the surface periodic relief occurs. Thus, the
optical modes interact with a surface and excite the
surface polaritons [6].
On the plots of the photoconductivity dependence
on the angle of the electromagnetic radiation incidence,
we observed the maxima in the case of the normal
incidence in the region of the angle of the total internal
reflection respectively to macropore walls, and at a
grazing angle of incidence respectively to the structure
surface.
Franz-Keldysh oscillations were registered in
electroreflectance spectra of the macroporous silicon
structures [7]. The oscillation period corresponds to the
built-in electric field of (5…9)⋅105 V/cm. It is caused by
the surface conditions at the interface silicon – oxide
silicon, which generate the two-dimensional electron gas
enriched layer of 0.6 to 1 nm thickness.
It is established that maxima of photoconductivity
are observed in the field of intrinsic absorption, on a
surface bonds, C-H, Si-H bonds, generated on a surface
after electrochemical etching (Fig. 5). Thus, the
photoconductivity is determined by generation of
photocarriers at the surface in the enriched layer.
Correspondence of the photoconductivity spectra of
macroporous silicon structures and those of monocrystal
silicon testifies to the enrichment of a macropore surface
by photocarriers and formation of the plasmon type
surface polaritons in this spectral region [4, 6].
The enhancement of the photoconductivity is shown
in Fig. 6a where the spectral dependence of
photoconductivity is presented in the region of band-to-
band light absorption of monocrystalline silicon and
structures of macroporous silicon. It can be seen from
Fig. 6a that, in the macroporous silicon structures, the
signal of photoconductivity is higher by a factor of 30
than that for a single crystal substrate. At the maximal
enhancement of photoconductivity (Fig. 6a, curve 4), the
peak shift into the longwave region is measured. The
dependence of maximum of photoconductivity spectrum
signal on the distance between macropores a – Dp is
presented in Fig. 6b. The greatest value of the
photoconductivity signal is measured at the distance
between macropores a – Dp = 2 μm.
The photoconductivity relaxation time of
macroporous silicon structures comprises values 20 to
80 μs at Т = 300 K, which is by the order larger than the
relaxation time for monocrystalline silicon (Fig. 7).
The dependence of electronic conductivity on the
intensity of illumination for macroporous silicon
structures measured at 0.9 μm wavelength is shown in
(Fig. 8). There were revealed the linear dependence of
photoconductivity at the intensity of illumination within
the range 2⋅1012 to 4⋅1012 quantum/(сm2⋅s), the power
dependence with an exponent 1/5 within the range of
intensities 5⋅1012 to 4⋅1013 quantum/(сm2⋅s), and the
saturation within the range 5⋅1013 to
3⋅1014 quantum/(сm2⋅s) at Т = 78 К. The power
dependence with an exponent 1/5 is classical [8]. It
shows the increase in surface potential due to increasing
the concentration of photocarriers for macropore
surfaces. In this case, the increase in the surface potential
can be caused by the formation of surface polaritons.
Thus, the significant charge of nonequilibrium carriers
can be collected as a result of decreasing the surface
recombination rate. The measured photoresponse is
increased with the intensity of illumination almost by the
order of its values at room temperatures (Fig. 8). It is the
result of accelerated photocarrier recombination. The
Hall measurements showed that the growth of
conductivity at linear and power parts of the
dependences on the light intensity is caused by the
increased electron mobility.
The objects of the further researches are theoretical
estimations of processes in the field of a spatial charge
(1), the contribution of surface levels and electronic gas
of the enriched layer into the magnitude of
photoconductivity (2), and peculiarities of electron
scattering by the macropore surface potential in
connection with the surface polariton formation.
4. Conclusions
Photoconductivity is measured in structures of
macroporous silicon. There are maxima of
photoconductivity observed at the normal incidence of
the electromagnetic radiation, at angles close to the total
internal reflection angle relatively to macropore walls,
and at grazing light incidence relatively to the surface of
the structure.
The angular dependences of photoconductivity, its
amplification, formation of optical modes and realization
of a single-mode regime, essential exceeding the
absorption over reflection of light by structures of
macroporous silicon are caused by the interaction of
optical modes with amplitude fluctuations of oscillators
at the macropore surface and with the surface polariton
formation.
The photoconductivity bands correlate with maxima
of intrinsic and impurity light absorption. The absolute
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 4. P. 425-429.
© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
429
maximum of photoconductivity is observed when the
distance between macropores a – Dp = 2 μm.
Photoconductivity is mainly determined by the growth
of the electron mobility.
References
1. L.A. Karachevtseva, O.A. Litvinenko, E.A.
Malovichko, Stabilization of electrochemical
formation of macropores in n-Si // Journ. of Theor.
and Experim. Chem. 34 (5), p. 314-318 (1998).
2. L.A. Karachevtseva, O.A. Lytvynenko, O.J. Stronska,
Development and optical characteristics of the
macroporous silicon structures // Semiconductor
Physics, Quantum Electronics & Optoelectronics, 3
(1), p. 22-25 (2000).
3. L.A. Karachevtseva, O.A. Litvinenko, E.A.
Malovichko, O.J. Stronska, Optical transmittance of
2D macroporous silicon structures // Ibid. 4 (4), p.
347-351 (2001).
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Surface polaritons in semiconductors and dielectrics,
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F.F. Sizov, Enhancement of the photoconductivity in
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Photonic Crystal Materials and Devices II, Proc.
SPIE, 5360, p. 381-389 (2004).
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Litvinenko, L.A. Karachevtseva, Electroreflectance
study of macroporous silicon structures // Appl. Surf.
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presurface semiconductor layers, Naukova Dumka,
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