Photoluminescence study of ZnSe single crystals grown by solid-phase recrystallization

Abstract

We investigate through low-temperature photoluminescence (PL) and selective photoluminescence (SPL) spectroscopies, ZnSe single crystals grown by solid-phase recrystallization. The PL spectra are dominated by the so-called I1deep excitonic line, a neutral–acceptor bound–exciton line I1, the free-exciton emission FX, and the n=2 excited state of FX. We identify the main residual impurities. Donor–acceptor pair bands are hardly detected. A major characteristic of these samples is the quasiabsence of any Cu-related deep emission which generally plagues the PL spectra of bulk ZnSe. Consequently, I1deep is ascribed to an exciton bound to Zn-vacancies related acceptors. Our results indicate that these ZnSe samples are of high quality and that solid-phase recrystallization is a promising technique to prepare ZnSe epitaxial substrates.