Effect of Film Thickness on Structural Stability for BAlN and BGaN Alloys: Bond‐Order Interatomic Potential Calculations

Abstract

The effects of film thickness on the relative stability among fivefold coordinated hexagonal and fourfold coordinated wurtzite and zinc blende structures in BAlN and BGaN alloys are theoretically investigated based on empirical bond‐order potential calculations. It is revealed that the trend of stable structure in BAlN alloys is different from that of BGaN alloys. The film thickness for the stabilization of the hexagonal structure increases with boron composition x for BxGa1–xN alloys, whereas the thickness decreases for BxAl1–xN alloys. The difference in the stabilization of the hexagonal structure between BxAl1–xN and BxGa1–xN alloys is due to the inhibition of in‐plane lattice relaxation in BxAl1–xN alloys. These results suggest that our approach using the bond‐order potential is feasible to investigate the stability of alloy systems with not only tetrahedrally coordinated forms such as the wurtzite and zinc blende structures but also specific forms containing the fivefold coordinated hexagonal structure.