Antisites in III-V semiconductors: Density functional theory calculations

Density functional based simulation, corrected for finite size effects, is used to investigate systematically the formation of antisite defects in III-V semiconductors (III = Al, Ga, and In and V = P, As, and Sb). Different charge states are modelled as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites ( IIIVq) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites ( VIIIq) show a consistent decrease in formation energies with increase in group III and group V covalent radii. In general, IIIVq defects dominate under III-rich conditions and VIIIq under V-rich conditions. Comparison with equivalent vacancy formation energy simulations shows that while antisite concentrations are always dominant under stoichiometric conditions, modest variation in growth or doping conditions can lead to a significantly higher concentration of vacancies.