HOPPING TRANSPORT ON A FRACTAL - AC CONDUCTIVITY OF POROUS SILICON

被引:182
作者
BENCHORIN, M [1 ]
MOLLER, F [1 ]
KOCH, F [1 ]
SCHIRMACHER, W [1 ]
EBERHARD, M [1 ]
机构
[1] TECH UNIV MUNICH, DEPT PHYS E13, D-85747 GARCHING, GERMANY
来源
PHYSICAL REVIEW B | 1995年 / 51卷 / 04期
关键词
D O I
10.1103/PhysRevB.51.2199
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We have measured the frequency dependence of the conductivity and the dielectric constant of various samples of porous Si in the regime 1 Hz to 100 kHz at different temperatures. The conductivity data exhibit a strong frequency dependence. When normalized to the dc conductivity, our data obey a universal scaling law, with a well-defined crossover in which the real part of the conductivity changes from an 1/2 dependence to being proportional to. We explain this in terms of activated hopping in a fractal network. The low-frequency regime is governed by the fractal properties of porous Si, whereas the high-frequency dispersion comes from a broad distribution of activation energies. Calculations using the effective-medium approximation for activated hopping on a percolating lattice give fair agreement with the data. © 1995 The American Physical Society.
引用
收藏
页码:2199 / 2213
页数:15
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