Structural study of ZnS/ZnSe strained layer superlattice grown by molecular beam epitaxy

Rapid progress has been made in short wavelength (blue or ultra-violet) semiconductor lasers in recent years. Group II-VI compound semiconductors have been receiving particular attention because of their wide bandgap. Superlattices allow optical and electrical characteristics to be freely set due to the quantum effect, so they are often utilized in the active layer of high performance LD´s. ZnS is one of the wide bandgap materials among the II-VI compounds (3.6 eV at R.T.) and the ZnS/ZnSe strained layer superlattice (SLS) has a large band discontinuity so that effective light and carrier confinement are expected. This work fabricates ZnS/ZnSe SLSs on ZnSe buffer layer using GaAs(100) wafer grown by molecular beam epitaxy (MBE). A basic structural and optical study is performed on these films. The effect of strain on the bandgap is also investigated by calculating the tight binding model