Recombination of photogenerated charge carriers in nanoporous gallium phosphide

Using time resolved microwave conductivity experiments, the dynamics of charge carrier recombination in nanoporous GaP was studied. The photoinduced conductivity initially decays very rapidly on a microsecond timescale but slows down by eight orders of magnitude in its final stages. The experimental results can be explained by a model in which charge carrier recombination takes place at the semiconductor surface, the rate being determined by the band bending across the depletion layer. The conductivity response is characteristic for a situation where the typical length scale for the nanoporous semiconductor network (10(-7) m) is comparable to the width of the depletion layer.