Assessment of interatomic potentials for molecular dynamics simulations of GaAs deposition

Computational studies of atomic assembly processes during GaAs vapor deposition require interatomic potentials that are able to reasonably predict the structures and energies of a molecular arsenic vapor, a variety of elemental gallium and arsenic lattices, binary GaAs lattices, GaAs lattice defects, and 001 GaAs surfaces. These properties were systematically evaluated and compared to ab initio and experimental data for one Tersoff and two Stillinger-Weber SW GaAs interatomic potentials. It was observed that bulk and arsenic molecular properties calculated by the Tersoff parametrization matched density functional predictions and experimental observations significantly better than either of the SW parametrizations. These trends can be related to the bonding physics included in each potential format. Surface free energy calculations indicate that none of these potentials correctly predict the low-energy surface reconstructions of the GaAs 001 surface. Simulated As2 molecular bonding with gallium-rich GaAs 001 surfaces indicate a high sticking probability for SW potentials, which is in good agreement with experimental observations at low growth temperatures. However, the Tersoff parametrization resulted in an unphysically high desorption probability for As2 over a wide range of surface temperatures.