Physical Structure, Characteristics, and Applications of Monolithic Bidirectional Switches: A Comprehensive Review

Bidirectional switches (BiSs) own excellent characteristics, allowing bidirectional current flow during conduction period and withstanding bidirectional voltage when turned off. However, traditional BiSs are typically implemented by the association of unidirectional discrete devices, such as the series and antiparallel connection of two active devices and two diodes, which exhibit relatively large device size and conduction losses due to the on-state voltage offset. With the popularity of wide band-gap (WBG) semiconductor materials such as SiC and GaN, there is an urgent need to design BiSs with lower on-state voltage drop, smaller conduction losses, smaller device size, and consequently higher power density. Therefore, by integrating several power transistors into a single chip, monolithic bidirectional switches (MBSs) based on WBG semiconductor materials can achieve this goal very well, exhibiting high-frequency and fast switching while reducing parasitic inductance and conduction resistance. This article provides a comprehensive review of MBSs from the perspectives of materials, physical structures, characteristics, and applications for the first time, which is helpful for the in-depth optimization and future large-scale promotion of MBSs.