Near-Band-Edge Photoluminescence of Sulfur-Doped GaAs Prepared by Liquid Phase Epitaxy

Abstract

Photoluminescence measurement is used to characterize the sulfur-doped GaAs epitaxial layers grown on GaAs(100) substrates by liquid phase epitaxy. The dependences of spectral line shape on the doping levels ranged from 5×1017 to 1.8×1018 cm-3 as functions of excitation power and temperature have been investigated. Three main competing near-band-edge radiative transitions are identified as: direct conduction band to valence band transition, conduction band filling levels to valence band tail transition, and donor-related states to valence band tail or to acceptor transition. In order to explain the spectral shifting and broadening observed in heavily sulfur-doped GaAs, the luminescence peak emitted from the conduction band filling to valence band tail transition is also compared with theoretical calculations where the carrier concentration dependence of peak energy can be well described based on the heavy doping induced band-tail effect.