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

Abstract

Alternating current (AC) impedance measurements have been performed on 10-to 15-lm 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 r ac was found to increase with frequency f according to the universal power law: r ac ¼ 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.

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiOxCy:H) Films at the Amorphous-to-Nanocrystalline Transition Zone

“…Jonscher’s law can be used to characterize the observed conductivity curves for the low-frequency region where σ­( f ) is conductivity at frequency f , σ dc is the dc conductivity, and s stands for the frequency exponent. From Jonscher’s law fitting, the dc conductivity for each of the samples at different temperatures is obtained.…”