Interpretation of an anomalous peak in low-temperature photoluminescence measurements of bulk GaAs1−xNx on GaAs

Low-temperature (10K) photoluminescence measurements of GaAs1−xNx epitaxial layers grown on GaAs reveal an anomalous second peak in solid-source molecular beam epitaxy. Rapid thermal annealing (RTA) of a specific GaAsN sample reveals a lower energy peak (γ) which redshifts and a higher energy peak (α) which blueshifts under increasing annealing temperature. The band-anticrossing model is used to identify the origins of the two peaks and we propose a model to explain the RTA observations by the concept of increased confinement in areas of higher N concentrations by trapped N localized states. The γ peak is due to the accumulation of N content near the GaAs∕GaAsN interface. Hence, this abnormal annealing behavior occurs in layers with nonuniform N concentration at the GaAsN∕GaAs interface.