Structural, optical, and thermal properties of BN thin films grown on diamond via pulsed laser deposition

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors $(\mathrm{bandgap}>4.0\phantom{\rule{0.28em}{0ex}}\mathrm{eV})$, such as BN and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in situ heteroepitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this work, we grew BN thin film on (100) single-crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. The structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room-temperature cross-plane thermal conductivity of BN is 1.53 \ifmmode\pm\else\textpm\fi{} 0.77 W/mK, while the thermal conductance of the BN/diamond interface is $20\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{0.28em}{0ex}}\mathrm{MW}/{\mathrm{m}}^{2}\mathrm{K}$. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures.