A terahertz investigation of the conduction mechanism in porous silicon

Scope and method of study. The purpose of this study was to develop and validate a technique suitable for measuring porous silicon thin films. A Terahertz Differential Time Domain Spectroscopy (THz-DTDS) system was built and calibrated to measure the AC conductivity of porous silicon (PS) in the terahertz frequency region. A series of calibration routines were carried out to estimate the uncertainties and errors in the experiment. Several theoretical models were investigated to look into the measured frequency-dependent conductivity of porous silicon.; Findings and conclusions. Preliminary experimental results were obtained by measuring the conductivity response of porous silicon samples with a wide range of thicknesses and porosities. Theories such as Drude model, Localization-modified Drude model, Smith model and Effective medium theories were used to model the measured conduction response from porous silicon. The experimental results show that the real part of the conductivity follows the sub-linear power law or the universal dielectric response (UDR) at low frequencies and Smith model and the Super-linear Power Law (SLPL) governs the conduction response at high frequencies.