Investigation of diamond/Ga<sub>2</sub>O<sub>3</sub> and diamond/GaN hetero-p–n junctions using mechanical grafting
Imteaz Rahaman, Hunter D. Ellis, Botong Li, Mohammad Mohammadi, Yunshan Wang, Kai Fu
Abstract
Abstract Exploring hetero-p–n junctions between ultrawide bandgap (UWBG) semiconductors is critical for advancing our understanding of carrier transport and interface properties, which are key to enabling future high-power electronic applications. However, large lattice mismatches and difficulty in doping have made such investigations particularly difficult. In this study, we introduce a unified approach for forming diamond/ β -Ga 2 O 3 and diamond/GaN hetero-p–n junctions by mechanically grafting their bulk materials, without the use of interfacial layers or complex bonding processes. The mechanically grafted diamond/ β -Ga 2 O 3 junction demonstrates a turn-on voltage of ∼3.25 V and maintains stable electrical behavior up to 125 °C, with low hysteresis (⩽0.2 V at room temperature and ⩽0.7 V at elevated temperature). A remarkably low ideality factor of 1.28 and rectification ratios exceeding 10 6 underscore the quality of the junction. The diamond/GaN heterojunction, formed on both Ga-polar and N-polar surfaces, exhibits stable diode behavior with light emission, indicating efficient charge transport. Both configurations demonstrate near-ideal characteristics, with ideality factors of 1.30 (Ga-polar) and 1.06 (N-polar), and rectification ratios exceeding 10 6 and 10 4 , respectively. The Ga-polar junction also shows notably low hysteresis (<0.05 V at 10 μ A), outperforming its N-polar counterpart. These findings highlight mechanical grafting as a practical and reproducible approach for studying heterojunctions between lattice-mismatched UWBG semiconductors. This method enables direct investigation of interface behavior and junction performance, offering value for both research and education in UWBG semiconductor technologies.