Photoconductivity of ZnSe crystals under high excitation rates

The generation-recombination processes in high-resistivity, undoped ZnSe si ngle crystals as well as in ZnSe:Mg and ZnSe:Cu crystals were studied on th e basis of an investigation of the photoconductivity kinetics on excitation with nanosecond laser pulses of an under-bandgap photon energy. The parame ters of the recombination centres are estimated. It was established that th e laser-stimulated increase in the steady-state photoconductivity of undope d ZnSe crystals with a low accidental impurity concentration was mainly due to formation of the slow recombination centres. The effect of accumulation of laser-induced point defects and its role in the observed photosensitiza tion of highly pure ZnSe single crystals are discussed. The present results can be used in the design and analysis of various optoelectronic and optic al devices using this compound.