Effect of isotopic mass on the photoluminescence spectra of beta zinc sulfide

摘要

Zinc sulfide is a wide bandgap semiconductor which crystallizes in either thewurtzite modification (a-ZnS), the zincblende modification (b-ZnS) or as one ofseveral similar tetrahedrally coordinated polytypes. In this work, we report aphotoluminescence study of different samples of isotopically pure b-ZnScrystals, and crystals with the natural isotopic abundances, at 15 and 77 K.The derivatives of the free and bound exciton energies on isotopic mass havebeen obtained. They allow us to estimate the contribution of the zinc andsulfur vibrations to the bandgap renormalization energy by electron-phononinteraction. A two-oscillator model based on the zinc and sulfurrenormalization energies has been used to account for the temperaturedependence of the bandgap energy in ZnS. The results are compared with thosefound for other tetrahedrally coordinated semiconductors.