Photoluminescence of AlxGa1−xAs

Abstract

We present the results of a detailed study of the photoluminescence spectra of epitaxially grown Al_xGa_1−xAs for 0.16≤x≤0.58 and for temperatures between 1.6 and 300°K. At helium temperatures, the emission spectrum consists of a narrow band (half‐width ∼ 10 meV) and a broad band (half‐width ∼ 30 meV) for direct‐ as well as indirect‐gap alloys. From temperature and excitation intensity dependence and from time‐resolved spectra, we we have identified the broad band as due to distant donor‐acceptor pair recombination. The narrow band is very likely due to free‐ and bound‐exciton recombination. These identifications differ from those suggested by others. At room temperature, the emission spectrum consists of a single peak with a long high‐energy tail. This emission is due to the direct band‐to‐band transition even in the case of indirect band‐gap materials with xx.