Abstract
Various LPE GaAs/Ga1−XAlXAs layers and DH lasers of direct alloy composition (0⩽X≲0.35) have been excited by photoluminescence and current injection at 300 K, respectively. All samples emit a weak low-energy band (BIII), peaking at about 1.02 eV independent of material composition X and doping. The responsible deep-level centers therefore remain fixed energetically at 1.02 eV, relative to the (more distant) band edge, as the gap is varied. This striking feature and other characteristics support the hypothesis that BIII results from radiative recombination at defects which are very similar, if not identical, to those labeled E3 in literature on this