Investigation of thermal annealing process of GaN layer on sapphire by molecular dynamics

Molecular dynamics (MD) calculations have been performed to simulate the heteroepitaxial growth process of GaN on sapphire (0001) substrates and the thermal stability of the low-temperature GaN layer during the annealing process has been investigated. The MD simulations indicated that the surface morphology and the crystallinity of GaN thin layers grown on sapphire at low temperature of 800 K was amorphouslike and very rough. The surface atomic morphology of the low-temperature GaN layer was improved after the thermal annealing MD simulations at 1100 and 1200 K and showed atomically hexagonal structures. The crystallinity of the GaN epitaxial layer on the sapphire (0001) substrate is found to be strongly dependent on the temperature of annealing.