Ultrawide Bandgap Diamond/ε-Ga<sub>2</sub>O<sub>3</sub> Heterojunction pn Diodes with Breakdown Voltages over 3 kV
Jianguo Zhang, Ningtao Liu, Li Chen, Xun Yang, Haizhong Guo, Zefeng Wang, Ming-Qian Yuan, Xuejun Yan, Jianqun Yang, Xingji Li, Chongxin Shan, Jichun Ye, Wenrui Zhang
Abstract
Robust bipolar devices based on exclusively ultrawide bandgap (UWBG) semiconductors are highly desired for advanced power electronics. The heterojunction strategy has been a prevailing method for fabricating a bipolar device due to the lack of effective bipolar doping in the same UWBG material. Here, we demonstrate a unique heterojunction design integrating the p-type diamond and n-type ε-Ga 2 O 3 that achieves remarkable breakdown voltages surpassing 3000 V. Despite the lattice mismatch, the heteroepitaxial ε-Ga 2 O 3 film is established on the diamond substrate, forming an atomically sharp interface with C–O–Ga bonding and enabling the O-terminated diamond surface for constructing an effective rectifying heterojunction. The ultra-high-quality interface, together with the lightly doped diamond as the drift layer, largely weakens the commonly met electric field crowding effect in power diodes and provides a cost-effective thermal management route. This study provides an efficient heterojunction design to realize the potential of UWBG semiconductors for ultra-high-power applications.