Low temperature photoluminescence of GaAs-epitaxial layers

Abstract

Photoluminescence (PL) spectroscopy was performed at low temperature to assess the quality of MBE grown GaAs layers. Several PL features associated with free exciton (X) and donor bound excitons (D⁰, X and D⁺, X) for the unintentionally doped samples have been identified. For the Be-doped samples, the near edge luminescence associated with free exciton and donor bound exciton was unresolved. For this feature, the free exciton peak dominates at higher laser excitation. The Be-doped GaAs also showed an acceptor bound exciton doublet (A⁰, X) transition. There were three PL features observed in the Si-doped samples. These are the near-edge luminescence (D⁰, X), Si-acceptor (D⁰, Si⁰_As) located around 8300 Å, and an unindexed low intensity peak at around 8500 Å. It was noted that the Si-acceptor peak becomes prominent at 10K and quenches at increasing temperature. Overall results indicate that the GaAs epitaxial layers grown by molecular beam epitaxy is of very good quality except forthe Si-doped GaAs.