Interfacial Microstructure Evolution of (B, Al)N Films Grown on Diamond Substrates

This study reports on the deposition of c-axis oriented boron-aluminum nitride ((B, Al)N) layers on polycrystalline and single crystal (111) diamond substrates using a magnetron co-sputtering system. In this study, the lattice mismatch between (B, Al)N and diamond appears to be an important factor in the mechanism behind the growth of (B, Al)N on diamond. Diamond has a significantly tighter lattice than (B, Al)N, and the single (111) diamond substrate has the same lattice symmetry as that of aluminum nitride (AlN) (0002). X-ray diffractometry and transmission electron microscopy were employed to analyze the microstructure of (B, Al)N films on both substrates, and the results showed a continuous variation in structure, from randomly oriented nano-grains to c-axis oriented columns. In addition, the (B, Al)N film exhibited a thinner, randomly oriented nano-grain layer on single crystal (111) diamond than on polycrystalline diamond.