Giant Enhancement of Hole Mobility for 4H-Silicon Carbide through Suppressing Interband Electron–Phonon Scattering
J. R. Sun, Shouhang Li, Zhen Tong, Cheng Shao, Meng An, Xiongfei Zhu, Chuang Zhang, Xiangchuan Chen, Renzong Wang, Yucheng Xiong, Thomas Frauenheim, Xiangjun Liu
Abstract
4H-silicon carbide (4H-SiC) possesses a high Baliga figure of merit, making it a promising material for power electronics. However, its applications are limited by low hole mobility. Herein, we found that the hole mobility of 4H-SiC is mainly limited by the strong interband electron-phonon scattering using mode-level first-principles calculations. Our research indicates that applying compressive strain can reverse the sign of crystal-field splitting and change the ordering of electron bands close to the valence band maximum. Therefore, the interband electron-phonon scattering is severely suppressed and the electron group velocity is significantly increased. The out-of-plane hole mobility of 4H-SiC can be greatly enhanced by ∼200% with 2% uniaxial compressive strain applied. This work provides new insights into the electron transport mechanisms in semiconductors and suggests a strategy to improve hole mobility that could be applied to other semiconductors with hexagonal crystalline geometries.