AC Impedance Studies on Metal/Nanoporous Silicon/p-Silicon Structures

M F Mabrook,A K Ray

doi:10.1007/s11664-016-5139-4

Abstract

Alternating current (AC) impedance measurements have been performed on 10- to 15-μm thick porous silicon layers on a (100) p-type silicon (p(+)Si) substrate with the aluminium (Al) top electrode in a sandwich configuration in the range of 20 Hz–1 MHz and in the temperature ranging between 152 K and 292 K. The ac conductivity σac was found to increase with frequency f according to the universal power law: sigma_{text{ac}} , = ,,Af^{s} where the exponent s is a frequency and temperature-dependent quantity. A hopping process is found to be dominant at low temperatures and high frequencies, while a thermally activated free band process is responsible for conduction at higher temperatures. Capacitance is found to decrease with frequency but increase with temperature. Frequency dependence of the loss tangent is observed with a temperature-dependent minimum value.

Highlights

Porous silicon (PS) has attracted considerable interest over the last 20 years from both academic and industrial research communities for its luminescence (EL) properties because of the large surface to volume ratio.[1]
We report the results of Alternating current (AC) conductivity and capacitance measurements on the Al/PS/p(+)Si/Al structure in the frequency range of 20 Hz–1 MHz and over the temperature range of 152–292 K
An investigation of the frequency and temperature-dependence of the AC conductivity in PS suggests that the electrical conduction at low temperatures is essentially dominated by hopping of charge carriers through the PS layer

Summary

Introduction

Porous silicon (PS) has attracted considerable interest over the last 20 years from both academic and industrial research communities for its luminescence (EL) properties because of the large surface to volume ratio.[1]. We report the results of AC conductivity and capacitance measurements on the Al/PS/p(+)Si/Al structure in the frequency range of 20 Hz–1 MHz and over the temperature range of 152–292 K. The conductivity exhibits a significant frequency-dependent behavior at low temperatures Ti £ 200 K.

Results

Conclusion