Luminescence in As-Grown ZnSe Crystals Containing Cu Impurity

Abstract

At low temperatures, as-grown zinc selenide crystals containing Cu as major impurity show three luminescent bands, i.e. green (5300 A), yellow (5700 A), and red (6400 A). Experimental studies were made of excitation spectra of these luminescences and photoconductivity at and above 77°K. Decay kinetics of these emissions and effects of infrared-irradiation are also presented at 77°K. The yellow emission can be attributed to the donor-acceptor pair recombination from spectral shift to longer wavelengths with time during decay. The red emission has the same excitation spectra as the photoconductivity and is quenched by infrared light simultaneously with photoconductivity under steady excitation. During decay this emission does not exhibit spectral shift and is stimulated by infrared light. These facts indicate the free electron to bound hole transition as the recombination mechanism. Conclusive argument cannot be given for the green emission which shows no spectral change during nonexponential decay.