Superlattice stacking structure in InGaN thin film pseudomorphic to GaN (0001) substrate: Semigrand canonical Monte Carlo simulation

Superlattice stacking structures in the Ga-rich branch of wurtzite In _xGa_1-xN/GaN were found using semigrand canonical Monte Carlo simulations, which were performed aiming at the construction of the alloy phase diagram [Mori et al., Mater. Phys. Mech. 6, 49 (2003)]. Simulated systems were In_xGa_1-xN thin films pseudomorphic to the GaN (0001) substrate. Continuing the simulations, we revealed that In-rich layers parallel to the substrate were formed in Ga-rich regions. At 800 K, traversing along the c direction GGGIGGGI⋯ superlattice-type stackings were more frequently observed, where G and I indicate the Ga-rich and In-rich layers, respectively. As the temperature increased along the two-phase boundary the superlattice structure changes so that many In-rich layers were included. The In content of the Ga-rich phase eventually exceeded 0.5 at a higher temperature such as 875 K.