Investigation of wurtzite (B,Al)N films prepared on polycrystalline diamond

The growth of epitaxial GaN on polycrystalline diamond using highly c-axis orientated AlN as a buffer layer is an attractive application for heat dissipation of LED devices. In this study, the (B,Al)N layer was used to bridge the gap of lattice mismatch between diamond and AlN. For the preparation of (B,Al)N films on a diamond substrate, an aluminum target was sputtered in DC mode and hBN in RF mode simultaneously in a pure nitrogen plasma. The results showed boron content in (B,Al)N film which were determined by X-ray photoelectron spectroscopy (XPS) increased with increase of RF sputtering power. The lattice constant of (B,Al)N films were smaller than pure AlN, suggesting the substitution of smaller boron atoms at Al positions. As the boron content increased, the crystallinity of (B,Al)N films decreased. The crystal qualities of AlN films was analyzed by rocking curve, and AlN was deposited on low boron content (B,Al)N layer with higher c-axis preferential orientation than if it had been grown on diamond directly.