Giant enhancement of hole mobility for 4H-silicon carbide through suppressing interband electron-phonon scattering

TL;DR

Applying compressive strain to 4H-Silicon Carbide significantly suppresses interband electron-phonon scattering, leading to a 200% increase in hole mobility, which enhances its potential for power electronic applications.

Contribution

This study reveals that uniaxial compressive strain can reverse crystal-field splitting and drastically improve hole mobility in 4H-SiC by suppressing interband electron-phonon scattering.

Findings

Hole mobility can be increased by 200% with 2% compressive strain.

Interband electron-phonon scattering is the main mobility limiter in 4H-SiC.

Strain engineering offers a new strategy to enhance semiconductor performance.

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 its 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 out-of-plane hole mobility of 4H-SiC can be 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.