Band offsets of epitaxial cubic boron nitride deposited on polycrystalline diamond via plasma-enhanced chemical vapor deposition

Abstract

Cubic boron nitride (c-BN) has been deposited on nitrogen-doped polycrystalline diamond films via plasma-enhanced chemical vapor deposition employing fluorine chemistry. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the c-BN/diamond interface. TEM observations indicated local epitaxy of c-BN on diamond, while h-BN was also observed at the interface. XPS measurements indicated that c-BN growth continued after nucleation. The band offsets between c-BN and diamond were deduced from XPS measurements. The c-BN valence band maximum (VBM) was 0.8 ± 0.1 eV above the diamond VBM, which corresponded to the c-BN conduction band minimum (CBM) of 1.7 ± 0.1 eV above the diamond CBM. Comparison with offsets predicted by theoretical calculations suggests that a C-N interface was obtained.