Investigation of persistent photoconductivity in a Ge-doped ZnSe epilayer

A persistent photoconductivity (PPC) measurement was made on Ge-doped ZnSe using contact electrodes. It is shown that Ge in ZnSe forms deep levels responsible for the observed PPC effect at a quenching temperature of 210 K. The photogenerated carriers move freely in the ZnSe:Ge epilayer but are confined in the region exposed to light, indicating that it is possible to write an erasable metallic pattern on the epilayer.