Sun Jianshi, Li Shouhang, Tong Zhen, Shao Cheng, An Meng, Zhu Xiongfei, Zhang Chuang, Chen Xiangchuan, Wang Renzong, Xiong Yucheng, Frauenheim Thomas, Liu Xiangjun
Institute of Micro/Nano Electromechanical System and Integrated Circuit, College of Mechanical Engineering, Donghua University, Shanghai 201620, People's Republic of China.
Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 10 Boulevard Thomas Gobert, 91120 Palaiseau, France.
Nano Lett. 2024 Aug 28;24(34):10569-10576. doi: 10.1021/acs.nanolett.4c02730. Epub 2024 Aug 6.
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.
4H 碳化硅（4H-SiC）具有较高的巴利加优值，使其成为电力电子领域一种很有前景的材料。然而，其应用受到低空穴迁移率的限制。在此，我们通过模式级第一性原理计算发现，4H-SiC 的空穴迁移率主要受带间电子 - 声子散射的限制。我们的研究表明，施加压缩应变可以反转晶体场分裂的符号，并改变接近价带最大值处电子能带的排序。因此，带间电子 - 声子散射受到严重抑制，电子群速度显著增加。施加 2% 的单轴压缩应变时，4H-SiC 的面外空穴迁移率可大幅提高约 200%。这项工作为半导体中的电子输运机制提供了新的见解，并提出了一种改善空穴迁移率的策略，该策略可应用于其他具有六方晶体几何结构的半导体。
