Issue |
Europhys. Lett.
Volume 54, Number 2, April 2001
|
|
---|---|---|
Page(s) | 234 - 240 | |
Section | Condensed matter: electronic structure, electrical, magnetic, and optical properties | |
DOI | https://doi.org/10.1209/epl/i2001-00300-9 | |
Published online | 01 December 2003 |
Temperature-dependent electrical conduction in porous silicon: Non-Arrhenius behavior
1
Department of Chemical Engineering, Faculty of Engineering, Hiroshima University
1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
2
Materials Science & Engineering, Henry Samueli School of Engineering
University of California, Irvine, CA92697-2575, USA
Received:
2
August
2000
Accepted:
13
February
2001
A model for the temperature dependence of electrical conduction in a
porous silicon (PS) layer is introduced based on the consideration
that the onset of electrical conduction is dependent on the formation
of a continuous network of conducting sites extending the entire
thickness of a PS layer. At an arbitrary temperature, a PS layer
consists of both unblocked and blocked sites (blocking energies are
larger than thermal fluctuation energy). The fraction of unblocked
sites increases with temperature. At low temperatures () a PS
layer is mainly dominated by a continuous network of blocked sites,
while discrete unblocked sites do not form any continuous network
extending the entire thickness of a PS layer. At medium temperatures
(
) both continuous networks of unblocked and blocked
sites appear in a PS layer. And at higher temperatures (
), a
PS layer is mainly dominated by a continuous network of unblocked sites,
while discrete blocked sites do not form any continuous network
extending the entire thickness of a PS layer. Contrary to the prevalent
views, the overall temperature dependence of the electrical conductivity
of a PS is not always Arrhenius: it obeys a Vogel-Tammann-Fulcher
(VTF) law at
, becomes insulating at
, and exhibits the
Arrhenius behavior only for
. Both T1 and T2 are
found to increase with the decrease silicon nanocrytallites sizes. The
VTF behavior was derived using the mean-field approximation for Ising
model and found to agree with experimental evidences.
PACS: 73.23.-b – Electronic transport in mesoscopic systems / 73.50.-h – Electronic transport phenomena in thin films / 73.61.Tm – Nanocrystalline materials
© EDP Sciences, 2001
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