PHOTOLUMINESCENCE AND RAMAN-SCATTERING OF ZNSE ZNTE SUPERLATTICES

Optical properties of ZnSe-ZnTe superlattices grown on GaAs within critical thickness (about 2 nm) by molecular beam epitaxy are measured as a function of thickness ratio by photoluminescence and Raman scattering. High-quality superlattices are obtained by deposition of 500 cycles without buffer layers and their photoluminescence can be changed from blue to red color by the thickness ratio. Blue emission originates from exciton complexes of bound excitons at Te atoms and clusters. The frequency shift of ZnSe- and ZnTe-like phonons is explained well by an elastic model taking into account of lattice mismatch. The sound velocities estimated from the LA phonon folding observed by Raman scattering show hardening of the ZnSe lattice and softening of the ZnTe lattice.