Photoluminescence Studies Of Donors In MBE-Grown ZnSe

Abstract

Conventional photoluminescence (PL) and selectively-excited photoluminescence (SPL) techniques have been employed in order to identify donor species giving rise to features in the near-band-gap emission from ZnSe epitaxial layers grown on GaAs substrates by molecular beam epitaxy (MBE). Specifically, we have been interested in understanding the origins of the I20 and Ix peaks observed in MBE-grown ZnSe in several labs. A number of different impurity species have been identified on the basis of the energies of two-electron transition satellite peaks observed under resonant excitation into the donor-bound exciton manifold in the SPL experiments. Secondary ion mass spectrometer (SIMS) measurements have been performed on the same samples to provide supporting evidence for our assignments.We fins that some impurities which appear in SIMS only at their detectability limits (<10¹⁴ cm in some cases) can contribute significantly to the PL emission spectra. Implications of this study for improving the quality of MBE-grown films will be discussed.