Luminescence as a diagnostic of wide-gap II-VI compound semiconductor materials

The use of photoluminescence and related optical techniques to characterize the effects of strain and impurity levels in zinc selenide is reviewed. A theoretical discussion of the strain splittings occurring in heteroepitaxial ZnSe grown by molecular beam epitaxy or metalorganic chemical vapor deposition (MOCVD) on GaAs or other III-V substrates is given and compared to extensive experimental data. The binding energies and excited-stage energies of shallow acceptor levels due to N, Li, P, O, and two as-yet unidentified impurities are determined. The shallow acceptor level previously attributed to As is due to Li. The C impurities in MOCVD ZnSe have no observable effect on its opto-electronic properties but can stimulate relaxation of thermal strain at heavy doping levels. We investigate bound excitons involving N, Li, P, and two unidentified acceptor levels and show that Haynes's Rule linear relationship does not apply to acceptors in ZnSe.