New radiative deep states in epitaxial Ga1−xAlxAs

Abstract

Photoluminescence measurements performed at 6–7 K on intentionally undoped n‐type liquid‐phase epitaxy Ga_1−xAl_xAs (0.19⩽x⩽0.78) reveal transitions involving energies significantly lower than the band gap for crystals with x⩾0.47. Analysis of the luminescence data as a function of excitation intensity shows the presence of deep‐level acceptors which participate in radiative transitions, and binding energies of 0.52, 0.48, and 0.56 eV are obtained for x=0.47, 0.50, and 0.61, respectively. These values are strikingly similar to the activation energies of hole traps which are present in crystals with x=0.50, 0.61, and 0.78 and strongly suggests that the radiative acceptors and the hole traps are either identical or related states. Electron trap levels which are also present in the same crystal are found to be nonradiative.