【Member News】New Progress on the Breakdown Characteristics of Ga₂O₃-on-SiC MOSFET Made by Nanjing University of Posts and Telecommunications

      Recently, a team from the School of Integrated Circuit Science and Engineering, the National Local Joint Engineering Laboratory of RF Integration and Micro-assembly Technology, the Gallium Oxide Semiconductor Innovation Center, and the Nantong Research Institute of Nanjing University of Posts and Telecommunications published a paper article in the scientific journal Crystals titled Breakdown Characteristics of Ga₂O₃-on-SiC Metal-Oxide-Semiconductor Field-Effect Transistors.

Abstract

      Ga₂O₃ heterogeneous epitaxy based on silicon carbide (SiC) substrate can effectively mitigate the self-heating effect of Ga₂O₃ MOSFETs. The article verifies the effectiveness of this approach by reducing the lattice temperature of Ga₂O₃-on-SiC MOSFETs by about 100 °C compared to conventional homogeneous epitaxial Ga₂O₃ MOSFETs, thanks to the high thermal conductivity of SiC, as shown in Figure 1. However, due to the relatively low breakdown strength of SiC (3.2 MV/cm), the Ga₂O₃/SiC interface is susceptible to premature breakdown. To investigate this effect in depth, the paper presents a detailed study of the breakdown characteristics of Ga₂O₃-on-SiC MOSFETs using Sentaurus TCAD numerical calculations. The results show that in Ga₂O₃-on-SiC MOSFETs, the peak electric field in Ga₂O₃ is only 75% of its breakdown field strength when the SiC substrate reaches its critical breakdown field strength, as shown in Fig. 2. By optimizing the device structure, the premature breakdown effect of Ga₂O₃-on-SiC MOSFETs is significantly mitigated. The study reveals the premature breakdown effect in Ga₂O₃-on-SiC MOSFETs and proposes corresponding solutions, which provide a theoretical basis and guidance for the development of Ga₂O₃ power devices with high voltage withstand and high thermal conductivity.

Fig. 1 Lattice temperature distribution of (a) Ga₂O₃-on-SiC MOSFET and (b) conventional homogeneous substrate Ga₂O₃ MOSFET.

Fig. 2 (a) Two-dimensional electric field distribution in the Ga₂O₃-on-SiC MOSFET. (b) Distribution of the electric fields in the x-direction for the Ga₂O₃ and SiC layers, extracted from the red and yellow tangents in (a), respectively.

Paper link: https://doi.org/10.3390/cryst13060917