Diffusion Photovoltage in Porous Semiconductors and Dielectrics

Abstract

Strong retardation of photovoltage transients has been observed in porous materials (meso- and nanoporous Si, sintered networks of TiO2 nanoparticles, porous Al oxide) excited by short laser pulse. It has been shown that the photovoltage is mainly determined by the slow carriers diffusion with different diffusion coefficients for electrons and holes. The influence of particle dimension, sign of more mobile charge carriers, and surface conditioning on the diffusion photovoltage has been demonstrated. We propose the diffusion photovoltage method as a universal technique to study carrier diffusion in materials with very low conductivity.