Molecular dynamics simulation of cubic InxGa(1-x)N layers growth by molecular beam epitaxy

Abstract

The epitaxial growth of cubic InxGa1-xN layers on GaN (001) buffer substrates is investigated using molecular dynamics simulation. The substrate temperature, flux ratio of In, Ga, and N, In concentration, and thermal annealing post-growth were simulated and studied. The dislocation, the critical thickness, and the incorporation of the hexagonal phase into the cubic structure for InxGa1-xN are discussed in detail. Theoretical model conditions were simulated by Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) free-source code; the simulated growths reproduce the experimental thermodynamic conditions for molecular beam epitaxy process during the nucleation and first layers deposited. We consider the Stillinger-Weber In-Ga-N-system potentials. We apply time-and-position-dependent boundary constraints that vary the ensemble treatments of the near-surface solid-phase and the bulk-like regions of the growing layer. The results demonstrate that the simulations are suitable for reproducing the experimental epitaxial growths of cubic phase InGaN alloys with In concentration with 0 < x < 0.5. The hexagonal inclusion is a maximum of 5% for In < 0.2, indicating a preferential pure cubic structure. For In >0.2, the RMS roughness surface increase due to the inclusion of hexagonal planes parallel (110), (111), and (112) in cubic matrix. The average error for cubic phase percentage in the InGaN layers is <1% for x < 0.3, whereas for x = 0.48, the error is 4.8% compared with experimental results.