Diffusion photovoltage in porous semiconductors and dielectrics

Strong retardation of photovoltage transients has been observed in porous m aterials (meso- and nanoporous Si, sintered networks of TiO2 nanoparticles, porous Al oxide) excited hy short laser pulse. It has been shown that the photovoltage is mainly determined by the slow carriers diffusion with diffe rent diffusion coefficients for electrons and holes. nle influence of parti cle dimension, sign of more mobile charge carriers, and surface conditionin g on the diffusion photovoltage has been demonstrated. We propose the diffu sion photovoltage method as a universal technique to study carrier diffusio n in materials with very low conductivity.