Simulations of Nitrogen Incorporation into GaAsN Alloys: The Role of Lattice Relaxation

Due to the significant band gap narrowing induced by dilute fractions of N in III-V semiconductors, dilute nitride semiconductor alloys are of significant interest for long-wavelength optoelectronics. However, rapid thermal annealing (RTA) is often needed to achieve suitable transport properties and emission efficiencies. Therefore, identification of the local N environments and the influence of RTA on those environments is needed. For GaAsN, it has been suggested that N shares an As site with either As or N, with N-As and N-N pairs (split interstitials) aligned along [010] and [111] directions, respectively. However, the effect of lattice relaxation in the vicinity of incorporated N has not been considered. Here, we utilize density functional theory to compute minimum energy positions of NAs and surrounding neighbors. To identify N incorporation sites, we compare nuclear reaction analysis (NRA) spectra with Monte Carlo-Molecular Dynamics simulations along the [100], [110], and [111] directions. The measured NRA spectra exhibit the highest (lowest) yields in the [111]([100]) directions. Similar trends are observed for simulations of (N-As)As, confirming the presence of interstitial complexes, predominantly (N-As)As, in GaAsN.