Ultrawide-bandgap boron nitride thin films on diamond via pulsed laser deposition

Wide and ultrawide-bandgap (UWBG) semiconductors, such as GaN, Ga₂O₃, BN and diamond, and their epitaxial heterostructures hold significant importance for the development of next-generation high-power radio-frequency electronics. However, achieving in-situ hetero-epitaxy with ultra-clean defect-free interfaces, especially of BN/diamond heterostructures or vice-versa remains extremely challenging due to the complex growth kinetics and stability involved. Here, we have grown thin films of BN on single crystal diamonds by using pulsed laser deposition (PLD) and investigated its structural, magnetic, optical, and thermal properties. Detailed structural analyses (XPS, VBS, Raman, FTIR, and cross-sectional HRTEM, and EELS) confirms the growth of mixed phase BN on diamond, which exhibited diamagnetic behavior at room temperature. Film shows anisotropic refractive index (RI) within the visible-to-near-infrared wavelength range. Furthermore, we obtained room-temperature cross-plane thermal conductivity (<i>k</i>_^) of BN is ~1.53 W/mK, whereas the BN/diamond interface thermal conductance is ~20 MW/m²K. These findings are valuable for a wide-range of device applications based on BN/diamond heterostructures.<br/> <br/><b>Reference:</b> A. Biswas <i>et al.</i>, Phys. Rev. Materials <b>7</b>, 094602 (2023).<br/> <br/>The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. This work was sponsored in part by the Army Research Office and was accomplished under Cooperative Agreement Number W911NF-19-2-0269.