Using time resolved microwave conductivity experiments, the dynamics of cha
rge carrier recombination in nanoporous GaP was studied. The photoinduced c
onductivity initially decays very rapidly on a microsecond timescale but sl
ows 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 chara
cteristic for a situation where the typical length scale for the nanoporous
semiconductor network (10(-7) m) is comparable to the width of the depleti
on layer.