Prof. YE Jichun’s team from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), along with researchers from Zhengzhou University, Nanjing University, Harbin Institute of Technology and Yongjiang Laboratory, has developed high-performance diamond/ε-Ga2O3 heterojunction pn diodes based on ultrawide bandgap semiconductors, achieving breakdown voltages exceeding 3 kV.
The study was published in Nano Letters.
Ultrawide bandgap semiconductors using Ga2O3 and diamond show great potential for high-power applications, due to their ultrawide bandgap, high breakdown field, excellent radiation resistance, and great carrier mobility.
Bipolar devices, like pn diodes and bipolar junction transistors, enjoy promising prospects in the high-power electronics industry for their outstanding reverse voltage current tolerance.
However, effective bipolar doping in ultrawide bandgap semiconductors is limited by the substantial ionization energies of dopants. To address this bottleneck of bipolar doping, researchers at NIMTE proposed a heterojunction strategy integrating the p-type diamond and n-type ε-Ga2O3 for fabricating power pn diodes.
The heteroepitaxial n-type ε-Ga2O3 film was grown on the p-type diamond single-crystal substrate by the coordination of multi-domain and the confine of crystallization pathway to alleviate lattice mismatch. The heterojunction interface between ε-Ga2O3 and diamond is atomically sharp without observable interfacial element diffusion. This facilitates the highly efficient rectification and low reverse leakage current of the heterojunction diodes.
Compared with reported diamond-based diodes, the fabricated diamond/ε-Ga2O3 heterojunction diode shows superior rectifying characteristics with an on−off ratio over 108, and achieves a maximum breakdown voltage surpassing 3,000 V without any edge termination.
Besides, a thermal boundary conductance up to 64 MW/m2·K at 500 K was achieved, indicating the great thermal management capability of the diamond/ε-Ga2O3 heterojunction diode.
This work has provided a novel approach to fabricating high-performance ultrawide bandgap semiconductor-based bipolar devices with outstanding breakdown voltages and cost-effective thermal management capability for ultra-high-power applications.
The study was supported by the National Key R&D Program of China (Nos. 2022YFB3608604 and 2022YFA1404404), the National Natural Science Foundation of China (Nos. 62204244, 52394162, and 52027803), the Zhejiang Provincial Natural Science Foundation of China (No. LQ23F040003), and the Ningbo Yongjiang Talent Introduction Programme, etc.
Fig. The diamond/ε-Ga2O3 heterojunction pn diode with superior performance compared with other diamond diodes (Image by NIMTE)
Contact
Ye Jichun
Ningbo Institute of Materials Technology and Engineering
E-mail: jichun.ye@nimte.ac.cn