Varistor-like current-voltage characteristic of porous silicon
The porous silicon (PS) current-voltage characteristic (CVC) has measured in transverse and longitudinal applied electric field. The obtained CVC has a varistor-like shape. Besides the practical application this confirms the PS grain structure whose influence is discussed in analizing the mechanism...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1999
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Schriftenreihe: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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Zitieren: | Varistor-like current-voltage characteristic of porous silicon / O.V. Vakulenko, S.V. Kondratenko, B.M. Shutov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 88-89. — Бібліогр.: 7 назв. — англ. |
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irk-123456789-1190662017-06-04T03:03:44Z Varistor-like current-voltage characteristic of porous silicon Vakulenko, O.V. Kondratenko, S.V. Shutov, B.M. The porous silicon (PS) current-voltage characteristic (CVC) has measured in transverse and longitudinal applied electric field. The obtained CVC has a varistor-like shape. Besides the practical application this confirms the PS grain structure whose influence is discussed in analizing the mechanism of the visible luminescence in PS. 1999 Article Varistor-like current-voltage characteristic of porous silicon / O.V. Vakulenko, S.V. Kondratenko, B.M. Shutov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 88-89. — Бібліогр.: 7 назв. — англ. 1560-8034 PACS 72.80.Ng, s5.11 http://dspace.nbuv.gov.ua/handle/123456789/119066 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The porous silicon (PS) current-voltage characteristic (CVC) has measured in transverse and longitudinal applied electric field. The obtained CVC has a varistor-like shape. Besides the practical application this confirms the PS grain structure whose influence is discussed in analizing the mechanism of the visible luminescence in PS. |
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Vakulenko, O.V. Kondratenko, S.V. Shutov, B.M. |
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Vakulenko, O.V. Kondratenko, S.V. Shutov, B.M. Varistor-like current-voltage characteristic of porous silicon Semiconductor Physics Quantum Electronics & Optoelectronics |
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Vakulenko, O.V. Kondratenko, S.V. Shutov, B.M. |
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Vakulenko, O.V. |
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Varistor-like current-voltage characteristic of porous silicon |
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Varistor-like current-voltage characteristic of porous silicon |
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Varistor-like current-voltage characteristic of porous silicon |
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Varistor-like current-voltage characteristic of porous silicon |
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Varistor-like current-voltage characteristic of porous silicon |
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varistor-like current-voltage characteristic of porous silicon |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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1999 |
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http://dspace.nbuv.gov.ua/handle/123456789/119066 |
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Varistor-like current-voltage characteristic of porous silicon / O.V. Vakulenko, S.V. Kondratenko, B.M. Shutov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 88-89. — Бібліогр.: 7 назв. — англ. |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT vakulenkoov varistorlikecurrentvoltagecharacteristicofporoussilicon AT kondratenkosv varistorlikecurrentvoltagecharacteristicofporoussilicon AT shutovbm varistorlikecurrentvoltagecharacteristicofporoussilicon |
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88 © 1999, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1999. V. 2, N 2. P. 88-89.
1. Introduction
The notion of the nanocrystallites in randomly positioned
quantum wires or quantum walls between neighbouring pores
of the porous silicon (PS) samples has been applied by the
reseachers to explain a lot of photophysical effects, the vis-
ible photoluminescence in particular [1-3]. The availability
of such grain structure may also manifest itself in the PS
electrical properties. Hopefully, an asymmetric varistor-like
current-voltage characteristic (CVC) can be observed in the
structures with porous silicon layer. However, only asym-
metric diode-like CVC has been reported [4-7]. So, the ques-
tion about the existence of such grain structure could be sup-
plementary verified if one succeeded in finding varistor-like
CVC in the porous silicon samples. This has been the sub-
ject of our work. The problem of measuring CVC of PS in
longitudinal electric field, when both contacts are applied
to the PS side, lies in the fact that only PS layer has a larger
resistance in comparision with Si substrate. Consequently,
one should expect a short out effect by the material of Si
substrate. However, we succeeded in preparing the PS lay-
ers without the short out effect. These layers in the multilayer
structure of the PS, as all the others, consisted of Si nanocrys-
tallites in SiOx (0 < x < 2) matrix, but differed from others by
moderate oxidation. It is this moderate oxidation that favoured
the conductivity enhancement of the relevant sublayer of the
sample, as it has been reported [2,3]. Therefore, the partially
oxidated layers in PS have been investigated. In addition, these
layers showed a high-intensity visible photoluminescence.
PACS 72.80.Ng, s5.11
Varistor-like current-voltage characteristic
of porous silicon
O.V. Vakulenko, S.V. Kondratenko, B.M. Shutov .
Taras Shevchenko Kyiv Univ., 6 Glushkova Prosp., 252127 Kyiv, Ukraine
Tel. 8 044 266 01 62, E-mail: kondr@hq.ups.kiev.ua
Abstract. The porous silicon (PS) current-voltage characteristic (CVC) has measured in transverse and
longitudinal applied electric field. The obtained CVC has a varistor-like shape. Besides the practical
application this confirms the PS grain structure whose influence is discussed in analizing the mechanism
of the visible luminescence in PS.
Keywords: varistor, current-voltage characteristic, porous silicon.
Paper received 25.06.99; revised manuscript received 06.07.99; accepted for publication 12.07.99.
2. Experiment
The porous silicon samples were prepared using anodiza-
tion in 48% HF solution with a current density 25 mA/cm2
for ten minutes. (111) - oriented p-type silicon wafers were
used for substrates. Before anodization the substrates were
cleaned, and the ohmic contact was formed in a thin Al lay-
er on the back side of the Si substrate. The PS layer thick-
ness was approximately 5 µm. After anodizing a few semi-
transparant Au point contacts have been deposited onto the
PS surface (Fig.1). This made it possible to observe con-
point contact
P S
S i substrate
A l conta ct
Fig. 1. Structure with PS layer for CVC measurements.
s
O.V. Vakulenko et al.: Varistor-like current-voltage characteristic of porous silicon
89SQO, 2(2), 1999
ductivity in transverse and longitudinal applied electric field
in relation to the PS layer.
3. Results and discussion
Asymmetric diode-like current-voltage characteristic is al-
ways observed in transverse electric field measurments, be-
cause the porous silicon layer and the Si substrate give rise
to a rectifying contact.
According to the transverse field measurments, our sam-
ples have been divided into two groups. For the first one,
the current-voltage characteristic is similar to that for two
oppositely switched diodes. This testifies that metal - PS
contact forms a potential wall. The other group of the sam-
ples exhibited a symmetric varistor-like CVC (Fig.2). The
CVC of these samples can be described by the equation:
I = B⋅Un, where B is the sample constant depending on a lot
of factors: preparation and storage conditions and many oth-
ers. Here n is the varistor nonlinearity coefficient. For the
majority of PS samples it varies from 4 to 5. The CVC of the
sample showed in Fig.2 exhibits the magnitude of n ≈ 4.2.
The varistor-like CVC points to the fact that potential
wall on the PS - Au contact interface is absent for this type
of samples. The PS material nonlinearity is usually attribut-
ed to the varistor conductivity enhancement in increasing the
electric field intensity. In our case, it may be explained by the
following reasons: emission of electrons from grain edges of
the nanocrystallite structure formed in PS; large-field conduc-
tivity enhacement of the oxide film which covers the pores;
microheating of the contacting points between pores, etc.
The PS material irregularity does not make it possible to
choose one of the suggested reasons. However, the fact of ex-
istence of varistor-like CVC, besides the practical application,
is of interest, because it favours the grain, nanocrystallite PS
structure, whose influence is usually discussed in analyzing
the mechanisms of the visible photoluminescence in PS.
References
1. S.V. Svechnikov, A.V. Sachenko, G.A. Sukach, A.M. Yevstigneyev,
E.B. Kaganovich. Optoelektronika i poluprovodnikovaya tekhnika,
27, p. 3-29 (1994) (in Russian).
2. V.G. Golubev, A.V. Zherzdnev, G.K. Moroz, A.V. Patsekin, D.T. Yan.
Fizika i tekhnika poluprovodnikov, 30(5), p. 852-863 (1996) (in
Russian).
3. Y.Kanemitsu. Phys. Rev.B. 48(7),p. 4883-4886 (1993)
4. T.Ozaki, M.Araki, S.Yoshimura, H.Koyama, N.Koshida. J. Appl. Phys.
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p.2514-2516 (1992).
7. N.Koshida, M.Koyama, Appl. Phys. Lett. 60(3), p.347-349 (1992).
-20 -15 -10 -5
0 5 10 15 20
U, V
I , Am800
600
400
200
-200
-400
-600
-800
Fig. 2. Varistor-like CVC of the PS samples observed in longitudinally
applied electric field.
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