Effects of AlN substrate orientation on crystalline quality of wurtzite GaN films investigated via molecular dynamics

Abstract Molecular dynamics (MD) simulation was applied to investigate the deposition process of gallium nitride (GaN) films on aluminum nitride (AlN) substrates, in which the effects of different crystallographic orientations and growth temperatures of AlN substrates were investigated. Furthermore, evolution of the surface morphologies, the dislocations, the crystalline structures and the atomic stress were discussed in detail. It could be indicated that the deposited heteroepitaxial GaN films were consisted of zinc blende and wurtzite crystal structures with obvious dislocations when deposited on the polar plane of the AlN substrate. The dislocation density varied in a similar trend as the crystal structure changes. On the other hand, there is no misfit dislocations in the GaN films when deposition on the semi-polar and non-polar planes of the AlN substrate. According to the simulation results, the epitaxial GaN films deposited on the non-polar a-plane of the AlN substrates could be of higher crystalline quality under the same growth conditions.