Diffusion-controlled adecay of laser-excited photoconductivity in optoelectronic switches

When illuminating a semiconductor surface inhomogeneously, e.g. by a small laser spot, the photoexcited electrons and holes will partly diffuse into the dark or shaded semiconductor regions. The effect of such a carrier diffusion on measured decay of photoconductivity is studied quantitatively. The analysis yields a decay proceeding faster than linear recombination would imply. Particularly in the initial stages, the decay is quite similar to a plasma decay controlled by Auger recombination.