Photosensitive porous silicon based structures
We present results of electrical and photoelectrical measurements on two types of Al/porous silicon (PS)/monocrystalline silicon (c-Si)/Al sandwich structures with thin and thick PS layers obtained by stain etching. Current-voltage characteristics and photosensitivity spectra indicate that for struc...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1998
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| Zitieren: | Photosensitive porous silicon based structures / S.V. Svechnikov, E.B. Kaganovich, E.G. Manoilov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1998. — Т. 1, № 1. — С. 13-17. — Бібліогр.: 32 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860185354379722752 |
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| author | Svechnikov, S.V. Kaganovich, E.B. Manoilov, E.G. |
| author_facet | Svechnikov, S.V. Kaganovich, E.B. Manoilov, E.G. |
| citation_txt | Photosensitive porous silicon based structures / S.V. Svechnikov, E.B. Kaganovich, E.G. Manoilov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1998. — Т. 1, № 1. — С. 13-17. — Бібліогр.: 32 назв. — англ. |
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| container_title | Semiconductor Physics Quantum Electronics & Optoelectronics |
| description | We present results of electrical and photoelectrical measurements on two types of Al/porous silicon (PS)/monocrystalline silicon (c-Si)/Al sandwich structures with thin and thick PS layers obtained by stain etching. Current-voltage characteristics and photosensitivity spectra indicate that for structures with a thin PS layer the photosensitivity is determined by PS/c-Si heterojunctions (HJ), while for structures with a thick PS layer – by the PS layers themselves. The properties of PS/c-Si HJ were explained in the framework of a band diagram of the isotype HJ with opposite band bendings on the sides due to a high concentration of defect centers at the heterointerface. PS layers exhibit photoconduction with the photosensitivity maximum at 400–500 nm. The results are compared with those obtained for the structures based on PS layers prepared by electrochemical anodization.
Представлені результати електричних та фотоелектричних вимірювань двох типів Al/пористий кремній (ПК)/монокристалічний кремній (c-Si)/Al сендвич структур с тонкими та товстими шарами ПК, що одержані хімічним забарвлюючим травленням. Вольт-амперні характеристики та спектри фотовідгуків свідчать про те, що фоточутливість структур з тонкими шарами ПК переважно визначається гетеропереходом (ГП) ПК/c-Si, а з товстими . ПК шарами. Властивості ГП з.ясовані в рамках зонної діаграми ізотипного ГП з протилежними напрямками вигину зон по обидва боки переходу завдяки високій концентрації дефектів на межі розподілу. ПК шари . фоточутливі, з максимумом чутливості біля 400,500 нм. Результати порівнюються з такими для структур на основі шарів ПК, що одержані eлектрохімічним травленням.
Представлены результаты электрических и фотоэлектрических измерений двух типов Al/пористый кремний (ПК)/ монокристаллический кремний (c-Si)/Al сэндвич структур с тонкими и толстыми слоями ПК, полученными химическим окрашивающим травлением. Вольт-амперные характеристики и спектры фотооткликов свидетельствуют, что фоточувствительность структур с тонкими слоями ПК определяется гетеропереходом (ГП) ПК/c-Si, а с толстыми . ПК слоями. Свойства ГП объяснены в рамках зонной диаграммы изотипного ГП с противоположными направлениями изгибов зон по обе стороны перехода из-за высокой концентрации дефектов на гетерогранице. ПК слои . фотопроводящие с максимумом фоточувствительности при 400,500 нм. Результаты сравниваются с таковыми для структур на основе слоев ПК, полученных электрохимическим травлением.
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13© 1998 ²íñòèòóò ô³çèêè íàï³âïðîâ³äíèê³â ÍÀÍ Óêðà¿íè
Ô³çèêà íàï³âïðîâ³äíèê³â, êâàíòîâà òà îïòîåëåêòðîí³êà. 1998. Ò. 1, ¹ 1. Ñ. 13-17.
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1998. V. 1, N 1. P. 13-17.
ÓÄÊ 621.382, PACS 73.50.P; 47.55.M
Photosensitive porous silicon based structures
S. V. Svechnikov, E. B. Kaganovich, E. G. Manoilov
Institute of Semiconductor Physics, NAS Ukraine, 45 prospekt Nauki, Kyiv, 252028, Ukraine; E-mail: ebk@l-dif.semicond.kiev.ua
Abstract. We present results of electrical and photoelectrical measurements on two types of Al/porous
silicon (PS)/monocrystalline silicon (c-Si)/Al sandwich structures with thin and thick PS layers ob-
tained by stain etching. Current-voltage characteristics and photosensitivity spectra indicate that for
structures with a thin PS layer the photosensitivity is determined by PS/c-Si heterojunctions (HJ), while
for structures with a thick PS layer � by the PS layers themselves. The properties of PS/c-Si HJ were
explained in the framework of a band diagram of the isotype HJ with opposite band bendings on the
sides due to a high concentration of defect centers at the heterointerface. PS layers exhibit photoconduc-
tion with the photosensitivity maximum at 400�500 nm. The results are compared with those obtained
for the structures based on PS layers prepared by electrochemical anodization.
Keywords: porous silicon, photodiode, photoconduction, heterojunction.
Paper received 27.05.98; revised manuscript received 30.07.98; accepted for publication 28.10.98.
1. Introduction
Since the discovery of effective visible photoluminescence
(PL) at room temperature from highly porous silicon (PS), a
great deal of attention has been paid to its electronic proper-
ties because of the potential applications in Si-based
optoelectronics. Studies of the photoelectric properties of
PS covered such issues as transient and steady-state photo-
conductivity (PC) on self-supporting PS layers [1, 2], PC of
PS layers in metal (M)/PS/monocrystalline silicon (c-Si)/M
structures [3 � 5], persistent photocurrent at low (≤ 300 K)
temperatures, i.e., a photocurrent which has a very long de-
cay time after a short light exposure [6], photodiode proper-
ties of M/PS/c-Si/M structures [3, 5, 7�17], their photovoltaic
properties [18, 19], photo-emf and photoinduced charge trap-
ping in PS [19�22], and coordinate-sensitive lateral photo-
voltaic effect [23, 24].
When measuring electrical, photoelectric, and
electroluminescent properties of PS, or developing light-
emitting diodes and photodiodes, the heterojunction (HJ)
between PS and the c-Si substrate is an essential part of the
samples or device structures under investigation. However,
little is known about the electronic structures of PS/c-Si HJ
[12, 13, 17, 25]. It has been recently shown [12, 13, 17] that
properties of highly sensitive AL/PS/p-Si/Al photodetectors
were determined by band bending features at the PS/p-Si
heterointerface.
The structure of conventional PS-based photoelectric
systems is M/PS/c-Si/M, where PS layers with the thickness
ranging from several micrometers to ~ 100 µm are produced
by etching c-Si electrochemically with fluoric acid. How-
ever, anodization usually results in rough PS layers having
structural and optical inhomogeneities through their depth.
Meanwhile, purely chemical etching is simpler and can also
produce PS layers able to emit visible light similar to that of
PS layers fabricated by conventional anodization. Stain-
etched PS layers have a thickness below ~ 1 µm and are less
rough [26, 27].
This work is dealing with properties of Al/PS/p-Si/Al
photosensitive structures in which PS is obtained by chemi-
cal stain etching without applying electrical bias. The pur-
pose was to study electrical and photoelectrical properties
of such structures, to compare the results with those known
from literature for anodized PS layers, and to analyze them
in the framework of the accepted band diagram.
2. Experiment. Sample preparation
Conventional photosensitive structures consisting of a se-
ries combination of a M/PS contact, PS layer, and PS/c-Si
heterojunction do not allow separating the contributions of
the M/PS Schottky barrier, heterojunction barrier (contact),
and PS layer (bulk) to the electrical and photoelectric prop-
erties of the sample. Therefore, we formed two types of struc-
tures, with thin and thick PS layers. The contact contribu-
tion should prevail in the case of thin PS layers, of order
1 µm or less, while the bulk one should be dominant for
structures with thick PS layers. In both cases, samples were
formed from p-Si (100) with resistivity 10 Ω⋅cm. After clean-
ing, silicon wafers were immersed in the 1:3:5 (by volume)
solution of HF:HNO
3
:H
2
O. This solution was prepared us-
ing the standard electronic grade 49 % HF and 70 % HNO
3
.
The duration of etching typically ranged from 10 to 15 min.
S. V. Svechnikov et al.: Photosensitive porous silicon based structures
14 ÔÊÎ, 1(1), 1998
SQO, 1(1), 1998
Cross-sectional analysis reveals a nonplanar surface with
a thin (less than 1 µm) porous layer of a relatively uniform
thickness and a weblike morphology.
Thick porous layers were also prepared by stain etching
of p-Si wafers subjected to a preliminary laser treatment [28].
The surface of a p-Si substrate was scanned with a YAG:Nd3+
laser beam (λ = 1.06 µm) operating in the free generation
mode (t
p
= 0.2 ms, E = 0.2 J); the scanning followed a present
pattern. This technique is based on the idea that the effi-
ciency of etching should be enhanced in the areas of p-Si
where the structure is disordered due to the processes of
recrystallization and defect formation stimulated by laser
irradiation. This approach allowed us to decrease substan-
tially the time required to grow on laser-treated areas PS
layers of the thickness of several micrometers (1�3 min)
and, thereby, to form a pattern of PS, to reduce the size of Si
nanocrystallites (nc-Si), and to increase the effective area of
the nc-Si/SiO
x
H
y
interface, i.e., to develop an intensively
disordered structure.
Under excitation with an N
2
laser (λ = 0.34 µm, t
p
=
= 7 ns), visible PL with a maximum at 650�750 nm was
observed only from the laser treated areas both for thick and
thin PS layers. PL decay spectra revealed fast short-wave
and slow long-wave bands, so that photoluminescent prop-
erties of these samples seem to be same as those of PS lay-
ers prepared by electrochemical etching [28, 29].
Rear ohmic contacts were produced by Al evaporation
followed by annealing, and front-side contacts (1×1 mm2) �
by evaporation of Al, Au, and In.
For measurements of static and dynamic current-volt-
age characteristics (I-V curves), voltage was increased and
decreased with a step of the magnitude 0.1 V and different
duration (0.1 s and 10 s). The time lags between the steps
and measuring the current using a digital electrometer were
200 ns. The transient current caused by applying a voltage
step to a capacitor decayed in 10 s. The spectral response of
the structures was measured in the wavelength range from
400 to 1000 nm with a standard photodetector circuit and a
bias of several volts. In addition, the spectral response was
measured in the open circuit mode.
3. Results and discussion
For the structures with thin PS layers, I-V curves measured
in the darkness exhibit a typical rectifying behavior
(fig. 1(a), curve 1). The rectification ratio at a bias of sev-
eral volts reaches the value of ~ 105. The positive direction
of voltage in this figure (forward current) corresponds to a
positive bias applied to p-Si. The reverse branch displays
current saturation, which is always clearly pronounced.
Analysis of the forward current gives the value of the series
resistance of PS amounting to several kiloohms, and the
ideality factor at small bias of approximately 2 to 3. For
some samples, the forward branch shows a sign of a revers-
ible breakdown of the heterojunction: a small saturation seg-
ment of the I-V curve is followed by a segment where the
current increases (fig. 1(a), inset).
-10 -8 -6 -4 -2 0 2 4 6 8 10
10
-9
10
-7
10
-5
10
-3
a
2
1
U, V
I, A
0 4 8
10
-6
10
-4
1
U, V
I, A
-0,6 -0,4 -0,2 0,0 0,2 0,4 0,6
0
1
2
b
0
1
2
Ix10
6
, A
I
sc
Uoc
U, V
Ix10
8
, À
21
-10 -8 -6 -4 -2 0 2 4 6 8 10
10
-9
10
-7
10
-5
c
2
1
U, V
I, A
0,0 0,5 1,0
10
-7
10
-6
10
-5
2
U, V
I, A
-10 -8 -6 -4 -2 0 2 4 6 8 10
10
-8
10
-7
10
-6
10
-5
d
U, V
I, A
0 4 8
10
-7
10
-5
10
-3 2
1
U, V
I, A
Fig. 1. I-V characteristics of Al/PS/p-Si/Al structures: static (a, b, c) and dynamic (d), with thin (a, b) and thick (c, d) PS layers , in the
darkness (1) and under illumination (2). The insets show various branches of I-V curves: with a saturation section followed by a section
of reversible breakdown (a), with a notch region (c), and for a structure with a thin PS layer (d).
S. V. Svechnikov et al.: Photosensitive porous silicon based structures
15ÔÊÎ, 1(1), 1998
SQO, 1(1), 1998
Under illumination, the I-V curve (fig. 1(a), curve 2) is
typical for a photodiode. At a reverse bias of several volts,
the ratio of current measured under illumination and in the
darkness is one to two orders. The photocurrent increases
with reverse bias very slowly. The open circuit voltage (V
oc
)
is about 0.25 to 0.3 V, and the sign of V
oc
corresponds to the
depletion band bending of p-Si (fig. 1(b), curve 2).
The forward branches of the dynamic I-V curves in the
dark and under illumination display hysteresis loops
(fig. 1(d), inset). This indicates the presence of slow traps
for holes. The reverse branches do not show any hysteresis.
The spectral dependence of photosensitivity peaks at
900 nm (fig. 2, curve 2), and has the same shape as that for
Si photodiodes. This indicates that the light absorption that
takes place in p-Si is dominant. The magnitude of photo-
sensitivity in the best samples is as high as ~ 0.1 A/W. With
a front-side Al contact of good transparency, the quantum
yield in the vicinity of the photosensitivity maximum is high
and close to unity.
The photoresponse spectrum curve measured in the open
circuit mode displays a change of the photoresponse sign in
the short-wave and long-wave regions (fig. 3).
For the structures with thick PS layers of low conduc-
tivity, the I-V curves measured in the darkness are symmetri-
cal and nonlinear. The ratio of current measured under illu-
mination (10-2 W/cm2) and in the darkness at a bias of sev-
eral volts is one or two orders of magnitude, and does not
depend on the polarity of the voltage applied. Some sec-
tions of the I-V curves measured under illumination display
notches indicating the presence of a built-in electric field
(fig. 1(c), inset). Hysteresis loops demonstrating the cap-
ture of holes on slow traps are seen on the forward and re-
verse branches of the I-V curves (fig. 1(d)). The photosen-
sitivity spectrum measured by us has a maximum in the
short-wave range of 400 � 500 nm (fig. 2, curve 1).
In this work, the results are analyzed in the framework
of a model which does not take into consideration the role
of the Al/PS Schottky barrier. Previous I-V measurements
for the structures with different metal films (Al, Cu, Au)
evaporated on thin and thick PS did not reveal any depend-
ence of barrier parameters on the specific metal. A similar
behavior of the M/PS interface was observed in [16], where
only the series resistance depended on the particular metal
evaporated (Ca, Mg, Sb, and Au). Analysis of the I-V and
capacitance-voltage curves [17] shows that the band bend-
ing near the M/PS interface can be neglected. The authors of
[12, 13] were also dealing with photosensitive Al/PS/c-Si/
Al structures, and came to the conclusion that the Al/PS con-
tact can be considered as a weakly rectifying one.
The above-mentioned results obtained for the structures
with a thin PS layer can be explained in the framework of
the energy band diagram for the isotype heterojunction be-
tween a wide-band PS (2 to 3 eV) and c-Si (1.1 eV) with
close charge carrier concentrations, taking into account the
interface states (fig. 4) [30, 31]. This kind of a diagram
formed by two rear-to-rear connected Schottky diodes was
proposed in [12] for sensitivity analysis of photodiode struc-
tures based on p-PS/p-Si heterojunctions. Indeed, saturation
of I-V curves in both directions and different polarity of
photoresponses are inherent to such a model, and are ob-
served in our experiments as well.
When the energy of quanta of the incident light exceeds
the band gap of p-Si, but is smaller than that of PS, light is
absorbed in p-Si, and the sign of photoresponse is deter-
mined by the charge of holes moving from the HJ interface
to the ohmic contact (positive photoresponse, see fig. 3) in
full accordance with a depletion-type band bending. When
the energy of quanta of the incident light reaches the band
gap of porous silicon, this gives rise to a photogeneration of
holes in PS. Negative photoresponse in the short-wave re-
gion associated with the movement of these photoholes from
the HJ interface into the PS depth agrees with the opposite
sign of the Schottky barrier from the PS side. Negative
photoresponse in the long-wave spectral region can be at-
tributed to photoexcitation of charge carriers from the sur-
face electronic states (SES) associated with interface traps
or to optical transitions from the valence band of porous sili-
con to the conductance band of c-Si.
Previously [13], a similar hysteresis and photoresponses
of different polarities were observed for Al/PS/p-Si/Al struc-
tures. However, for these structures the reverse current in-
creased linearly with bias, and the forward current could be
extrapolated by an exponential function. The authors of [13]
interpreted these results in the framework of a model of an
400 600 800 1000
0,00
0,02
0,04
0,06
21
λ, nm
R, A/W
Fig. 2. Photosensitivity spectra of Al/PS/p-Si/Al structures with
thick (1) and thin (2) PS layers.
400 600 800 1000
-0,10
-0,05
0,00
0,05
λ, nm
Uoc, V
Fig. 3. Photoresponse spectrum of an Al/PS/p-Si/Al structure with
a thin PS layer measured in the open-circuit mode.
S. V. Svechnikov et al.: Photosensitive porous silicon based structures
16 ÔÊÎ, 1(1), 1998
SQO, 1(1), 1998
isotype HJ whose energy band diagram has a small peak
and a hollow. Measurements of the photoinduced charge
trapped in PS [20] revealed the photo-emf component asso-
ciated with the depletion region in p-Si at the PS interface
and the presence of slow states at the porous surface.
The results obtained for the structures with a thick PS
layer indicate that their photosensitivity is determined by
the photoconductivity of porous silicon. Taking into account
the photoluminescent properties of the layers, these results
allow to introduce an energy band diagram that includes
quantum-size c-Si nanocrystallites with local states in the
quantum well and SiO
x
H
y
barrier layers in which the com-
position and height of potential barriers change depending
on the conditions of PS formation. Absorption of light is
determined by optical transitions between the local states in
c-Si nanocrystallites and between them and delocalized states
in the barrier layers.
Only drifting charge carriers can contribute to the pho-
toconductivity, but not those taking part in paired radiative
recombination and in radiative recombination via the sur-
face states of the crystallites. That is why the quantum yield
of photoconductivity is small. Therefore, the conditions
needed for high intensities of the photoluminescence and
photoconductivity are opposite. To increase the intensity of
PL, it should be difficult for charge carriers to escape from
Si nanocrystallites, while for high photoconductivity, on the
contrary, the potential barriers limiting the transport of charge
carriers should be lowered. Since the mobilities of charge
carriers in PS are small (they do not exceed 10-2 to
10-3 cm2/V⋅s [32]), and the product of drift mobility by charge
carrier lifetime is approximately equal to 10-10 cm2/V [1],
then even in strong electric fields the drift length of charge
carriers does not reach one micrometer. Therefore, a thin
layer of porous silicon can be used for increasing the collec-
tion factor of charge carriers.
The key questions defining the photoconductivity of
porous silicon are as follows: what is the medium and what
is the mechanism for charge carrier transport. Since PS is
nanocomposite, and its matrix consisting of porous hydro-
genated silicon oxide contains quantum wires and quantum
dots of c-Si, then charge carrier tunneling through barriers
between silicon nanocrystallites is possible, as well as trans-
port of carriers injected from silicon nanocrystallites through
the region of the interface and barrier layers. So, the locali-
zation and the mechanisms of transport can be distinguished
not only by the dependence on the layer preparation condi-
tions and their microstructure, respectively, but also by the
conditions of photoconductivity measurements: excitation
level, temperature, and electric field. Currently, studies of
the transport properties of photoconductive PS layers are
only at the initial stage.
In summary, I-V and spectral photoresponse character-
istics of Al/PS/c-Si/Al structures were measured. Unlike to
the conventional technique, the PS layers were prepared by
chemical etching, without applying the electric field. It was
shown that in such structures it is possible to achieve in a
more simple way not only photoluminescent, but also elec-
trical and photoelectrical properties similar to those of the
structures based on PS formed by anodization. Thin (less
than one micrometer) PS layers prepared by chemical etch-
ing can be made more homogeneous, with a smooth sur-
face, and lower leakage current. It is found that the
photodiode properties of these structures are determined by
the isotype p-PS/p-Si heterojunction, taking into account the
effect of localized states at the interface. The photosensitiv-
ity of structures in which the properties of M/PS and PS/c-
Si heterojunction barriers are not displayed is determined
by the photoconductivity of porous silicon, with the maxi-
mum of its spectral dependence near 400 to 500 nm. Hys-
teresis loops seen on the I-V curves indicate the presence of
slow traps in the PS layer.
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S. V. Svechnikov et al.: Photosensitive porous silicon based structures
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SQO, 1(1), 1998
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ÔÎÒÎ×ÓÂÑÒÂÈÒÅËÜÍÛÅ ÑÒÐÓÊÒÓÐÛ ÍÀ ÎÑÍÎÂÅ ÏÎÐÈÑÒÎÃÎ ÊÐÅÌÍÈß
Ñ. Â. Ñâå÷íèêîâ, Ý. Á. Êàãàíîâè÷, Ý. Ã. Ìàíîéëîâ
Èíñòèòóò ôèçèêè ïîëóïðîâîäíèêîâ ÍÀÍ Óêðàèíû
Ðåçþìå. Ïðåäñòàâëåíû ðåçóëüòàòû ýëåêòðè÷åñêèõ è ôîòîýëåêòðè÷åñêèõ èçìåðåíèé äâóõ òèïîâ Al/ïîðèñòûé êðåìíèé (ÏÊ)/
ìîíîêðèñòàëëè÷åñêèé êðåìíèé (c-Si)/Al ñýíäâè÷ ñòðóêòóð ñ òîíêèìè è òîëñòûìè ñëîÿìè ÏÊ, ïîëó÷åííûìè õèìè÷åñêèì
îêðàøèâàþùèì òðàâëåíèåì. Âîëüò-àìïåðíûå õàðàêòåðèñòèêè è ñïåêòðû ôîòîîòêëèêîâ ñâèäåòåëüñòâóþò, ÷òî
ôîòî÷óâñòâèòåëüíîñòü ñòðóêòóð ñ òîíêèìè ñëîÿìè ÏÊ îïðåäåëÿåòñÿ ãåòåðîïåðåõîäîì (ÃÏ) ÏÊ/c-Si, à ñ òîëñòûìè � ÏÊ ñëîÿìè.
Ñâîéñòâà ÃÏ îáúÿñíåíû â ðàìêàõ çîííîé äèàãðàììû èçîòèïíîãî ÃÏ ñ ïðîòèâîïîëîæíûìè íàïðàâëåíèÿìè èçãèáîâ çîí ïî îáå
ñòîðîíû ïåðåõîäà èç-çà âûñîêîé êîíöåíòðàöèè äåôåêòîâ íà ãåòåðîãðàíèöå. ÏÊ ñëîè � ôîòîïðîâîäÿùèå ñ ìàêñèìóìîì
ôîòî÷óâñòâèòåëüíîñòè ïðè 400�500 íì. Ðåçóëüòàòû ñðàâíèâàþòñÿ ñ òàêîâûìè äëÿ ñòðóêòóð íà îñíîâå ñëîåâ ÏÊ, ïîëó÷åííûõ
ýëåêòðîõèìè÷åñêèì òðàâëåíèåì.
ÔÎÒÎ×ÓÒËȲ ÑÒÐÓÊÒÓÐÈ ÍÀ ÁÀDz ÏÎÐÈÑÒÎÃÎ ÊÐÅÌͲÞ
Ñ. Â. Ñâº÷í³êîâ, Å. Á. Êàãàíîâè÷, Å. Ã. Ìàíîéëîâ
²íñòèòóò ô³çèêè íàï³âïðîâ³äíèê³â ÍÀÍ Óêðà¿íè
Ðåçþìå. Ïðåäñòàâëåí³ ðåçóëüòàòè åëåêòðè÷íèõ òà ôîòîåëåêòðè÷íèõ âèì³ðþâàíü äâîõ òèï³â Al/ïîðèñòèé êðåìí³é (ÏÊ)/
ìîíîêðèñòàë³÷íèé êðåìí³é (c-Si)/Al ñåíäâè÷ ñòðóêòóð ñ òîíêèìè òà òîâñòèìè øàðàìè ÏÊ, ùî îäåðæàí³ õ³ì³÷íèì çàáàðâëþþ÷èì
òðàâëåííÿì. Âîëüò-àìïåðí³ õàðàêòåðèñòèêè òà ñïåêòðè ôîòîâ³äãóê³â ñâ³ä÷àòü ïðî òå, ùî ôîòî÷óòëèâ³ñòü ñòðóêòóð ç òîíêèìè
øàðàìè ÏÊ ïåðåâàæíî âèçíà÷àºòüñÿ ãåòåðîïåðåõîäîì (ÃÏ) ÏÊ/c-Si, à ç òîâñòèìè � ÏÊ øàðàìè. Âëàñòèâîñò³ ÃÏ ç�ÿñîâàí³ â
ðàìêàõ çîííî¿ ä³àãðàìè ³çîòèïíîãî ÃÏ ç ïðîòèëåæíèìè íàïðÿìêàìè âèãèíó çîí ïî îáèäâà áîêè ïåðåõîäó çàâäÿêè âèñîê³é
êîíöåíòðàö³¿ äåôåêò³â íà ìåæ³ ðîçïîä³ëó. ÏÊ øàðè � ôîòî÷óòëèâ³, ç ìàêñèìóìîì ÷óòëèâîñò³ á³ëÿ 400�500 íì. Ðåçóëüòàòè
ïîð³âíþþòüñÿ ç òàêèìè äëÿ ñòðóêòóð íà îñíîâ³ øàð³â ÏÊ, ùî îäåðæàí³ eëåêòðîõ³ì³÷íèì òðàâëåííÿì.
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| id | nasplib_isofts_kiev_ua-123456789-114664 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1560-8034 |
| language | English |
| last_indexed | 2025-12-07T18:04:03Z |
| publishDate | 1998 |
| publisher | Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| record_format | dspace |
| spelling | Svechnikov, S.V. Kaganovich, E.B. Manoilov, E.G. 2017-03-11T15:56:51Z 2017-03-11T15:56:51Z 1998 Photosensitive porous silicon based structures / S.V. Svechnikov, E.B. Kaganovich, E.G. Manoilov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1998. — Т. 1, № 1. — С. 13-17. — Бібліогр.: 32 назв. — англ. 1560-8034 PACS 73.50.P; 47.55.M https://nasplib.isofts.kiev.ua/handle/123456789/114664 621.382 We present results of electrical and photoelectrical measurements on two types of Al/porous silicon (PS)/monocrystalline silicon (c-Si)/Al sandwich structures with thin and thick PS layers obtained by stain etching. Current-voltage characteristics and photosensitivity spectra indicate that for structures with a thin PS layer the photosensitivity is determined by PS/c-Si heterojunctions (HJ), while for structures with a thick PS layer – by the PS layers themselves. The properties of PS/c-Si HJ were explained in the framework of a band diagram of the isotype HJ with opposite band bendings on the sides due to a high concentration of defect centers at the heterointerface. PS layers exhibit photoconduction with the photosensitivity maximum at 400–500 nm. The results are compared with those obtained for the structures based on PS layers prepared by electrochemical anodization. Представлені результати електричних та фотоелектричних вимірювань двох типів Al/пористий кремній (ПК)/монокристалічний кремній (c-Si)/Al сендвич структур с тонкими та товстими шарами ПК, що одержані хімічним забарвлюючим травленням. Вольт-амперні характеристики та спектри фотовідгуків свідчать про те, що фоточутливість структур з тонкими шарами ПК переважно визначається гетеропереходом (ГП) ПК/c-Si, а з товстими . ПК шарами. Властивості ГП з.ясовані в рамках зонної діаграми ізотипного ГП з протилежними напрямками вигину зон по обидва боки переходу завдяки високій концентрації дефектів на межі розподілу. ПК шари . фоточутливі, з максимумом чутливості біля 400,500 нм. Результати порівнюються з такими для структур на основі шарів ПК, що одержані eлектрохімічним травленням. Представлены результаты электрических и фотоэлектрических измерений двух типов Al/пористый кремний (ПК)/ монокристаллический кремний (c-Si)/Al сэндвич структур с тонкими и толстыми слоями ПК, полученными химическим окрашивающим травлением. Вольт-амперные характеристики и спектры фотооткликов свидетельствуют, что фоточувствительность структур с тонкими слоями ПК определяется гетеропереходом (ГП) ПК/c-Si, а с толстыми . ПК слоями. Свойства ГП объяснены в рамках зонной диаграммы изотипного ГП с противоположными направлениями изгибов зон по обе стороны перехода из-за высокой концентрации дефектов на гетерогранице. ПК слои . фотопроводящие с максимумом фоточувствительности при 400,500 нм. Результаты сравниваются с таковыми для структур на основе слоев ПК, полученных электрохимическим травлением. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Photosensitive porous silicon based structures Фоточутливі структури на базі пористого кремнію Фоточувствительные структуры на основе пористого кремния Article published earlier |
| spellingShingle | Photosensitive porous silicon based structures Svechnikov, S.V. Kaganovich, E.B. Manoilov, E.G. |
| title | Photosensitive porous silicon based structures |
| title_alt | Фоточутливі структури на базі пористого кремнію Фоточувствительные структуры на основе пористого кремния |
| title_full | Photosensitive porous silicon based structures |
| title_fullStr | Photosensitive porous silicon based structures |
| title_full_unstemmed | Photosensitive porous silicon based structures |
| title_short | Photosensitive porous silicon based structures |
| title_sort | photosensitive porous silicon based structures |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/114664 |
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