【Domestic News】Top 30 Candidates for thnnual Advances in China’s Third-Generation Semiconductor Technology: Ultrawide Bandgap Diamond/ε-Ga₂O₃ Heterojunction pn Diodes with Breakdown Voltages over 3 kV

      To implement China’s innovation-driven development strategy, accelerate the cultivation of new quality productive forces, and highlight key technological advances in the nation’s third-generation semiconductor industry, the Program Committee of the 11th International Forum on Wide Bandgap Semiconductors & the 22nd China International Forum on Solid State Lighting (IFWS & SSLCHINA 2025) initiated the selection for the “Annual Top Ten Advances in China’s Third-Generation Semiconductor Technology.” In 2025, a total of 43 valid entries were collected and screened in compliance with the evaluation criteria. Based on expert voting by the Program Committee, 33 outstanding achievements have entered the final Top 30 candidates (in no particular order). These achievements will be introduced one by one—please stay tuned.

Ultrawide Bandgap Diamond/ε-Ga₂O₃ Heterojunction pn Diodes with Breakdown Voltages over 3 kV

      ——Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences; Yongjiang Laboratory; Zhengzhou University

      In collaboration with Yongjiang Laboratory and Zhengzhou University, the Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, has addressed the long-standing challenge of the lack of bipolar doping in ultrawide-bandgap semiconductors. By achieving key breakthroughs in heteroepitaxial integration of ultrawide-bandgap semiconductors and in the fabrication of high-voltage power devices, the team reported their results in Nano Letters on an ultrahigh-breakdown-voltage ultrawide-bandgap Diamond/Gallium Oxide heterojunction P–N diode.

      The fabricated Diamond/Gallium Oxide diode features an atomically sharp interface and a favorable type-II band alignment, together with an exceptionally high interfacial thermal conductance of up to 42 MW·m⁻²·K⁻¹, demonstrating outstanding thermal management capability. The device exhibits a rectification ratio exceeding eight orders of magnitude and achieves a breakdown voltage of over 3000 V without the use of edge termination structures. This work provides a new pathway for the development of high-performance ultrawide-bandgap bipolar power devices.

Academic and Industrial Significance

      This work holds substantial academic significance. By synergistically regulating the crystallization pathway and multidomain growth behavior of metastable Gallium Oxide, the study successfully achieved epitaxial growth of high-quality, n-type–doped ε-phase Gallium Oxide thin films with controllable doping on p-type (100)-oriented diamond substrates. X-ray photoelectron spectroscopy and atomic-scale structural characterizations reveal an atomically abrupt heterointerface without elemental segregation between the high-temperature–crystallized Gallium Oxide epilayer and the oxygen-terminated diamond. This heterostructure exhibits an ideal type-II band alignment, providing an innovative materials system and device paradigm to address the long-standing challenge of bipolar doping in ultrawide-bandgap semiconductors.

      In terms of key performance metrics, compared with previously reported diamond-based diodes, the fabricated heterojunction diode demonstrates a rectification ratio exceeding eight orders of magnitude and negligible leakage current under reverse biases above 3000 V. Device simulations predict a breakdown voltage exceeding 5000 V. Moreover, time-domain thermoreflectance (TDTR) measurements indicate that the heterointerface possesses an interfacial thermal conductance exceeding 40 MW·m⁻²·K⁻¹, with minimal impact from the relatively low thermal conductivity of Gallium Oxide. These results demonstrate that the device simultaneously achieves high breakdown capability, high efficiency, and excellent thermal management. This work therefore provides a critical technological pathway and a core device solution for the development of next-generation high-performance and highly reliable power electronic systems, such as those required for smart grids, rail transportation, and aerospace power supplies.

Innovation Metrics

      1.Developed an ultrawide-bandgap semiconductor heteroepitaxial integration technology, enabling the formation of an atomically sharp interface with an interfacial thermal conductance exceeding 42 MW·m⁻²·K⁻¹.

      2.Demonstrated the first ultrawide-bandgap heterojunction p–n diode in the field with a breakdown voltage exceeding 3 kV, while simultaneously exhibiting low on-state resistance and efficient thermal management required for power device applications.

Application Prospects

      The successful development of the Diamond/Gallium Oxide heterojunction diode opens broad prospects for its application in next-generation ultra-high-voltage power electronic systems. The core breakthrough of this work lies in the construction of a high-quality heterointerface, which effectively circumvents the intrinsic bottleneck of “bipolar doping difficulty” in ultrawide-bandgap semiconductors. Benefiting from a breakdown voltage exceeding 3000 V, outstanding interfacial heat dissipation capability, and low on-state resistance, the device leverages the exceptionally high thermal conductivity of diamond to mitigate the severe self-heating effect that has long limited Gallium Oxide due to its low thermal conductivity. This all–ultrawide-bandgap device architecture represents an ideal solution for operation under extreme conditions, and in particular provides a novel device platform for future high-voltage electric drive systems as well as radiation-hardened power electronics for aerospace and deep-space exploration applications.

Recommender’s Statement

      This work reports the world’s first ultrawide-bandgap semiconductor heterojunction p–n device with a breakdown voltage exceeding 3 kV. It proposes an innovative strategy to overcome the detrimental impact of heterointerface defects on the breakdown performance of power devices and reveals the tremendous potential of ultrawide-bandgap semiconductors in power electronics.

      — Wenrui Zhang (Researcher, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences)

Publication and Recognition

      This work has been reported by news outlets such as the Chinese Academy of Sciences and Phys.org, and was selected by the journal Functional Diamond as one of the year’s seven major research highlights.

      Ultrawide Bandgap Diamond/ε-Ga2O3 Heterojunction pn Diodes with Breakdown Voltages over 3 kV

      Jianguo ZhangNingtao LiuLi ChenXun Yang*Haizhong GuoZefeng WangMing-Qian YuanXue-Jun YanJianqun YangXingji LiChongxin Shan*Jichun Ye*Wenrui Zhang*

      链接：https://doi.org/10.1021/acs.nanolett.4c05446