Percolation transition of persistent photoconductivity in II-VI mixed crystals.

We have observed for the first time conductivity fluctuations in the persistent photoconductivity mode in II-VI mixed crystals with the magnitude following the percolation approach as ~ T — T, ~ s, where T, is the percolation threshold temperature. Experimental results have demonstrated that the random local-potential fluctuations induced by compositional fluctuations are responsible for the persistent pho-toconductivity observed in II-VI mixed crystals. Different behaviors resulting from the DX centers, the macroscopic barrier, and the random local-potential fluctuations are distinguished. There has been a considerable amount of experimental and theoretical effort directed towards the understanding of persistent photoconductivity