First-principles study of the electronic structure of 2 H-, 3C-, 4 H-, and 6 H-silicon carbide under strain

Numerous silicon carbide (SiC) polymorphs are wide-bandgap (BG) and low carrier concentration semiconductors, which have been extensively applied in high-temperature, frequency, power, and voltage electronic and optoelectronic devices. Comprehensively understanding the electronic structure of SiC is of practical significance and an indispensable necessity. In this work, the first-principles calculation based on density functional theory is applied to probe the electronic structures of polymorphs (2 H-, 3C-, 4 H-, and 6 H-) SiC under compressive and tensile strains (\(\epsilon \)). The mechanical properties of 2 H-, 4 H-, and 6 H-SiC exhibit very analogous characteristics: the BGs shrinking with the compressive strain rising; it increasing initially following by decreasing when stretch applied along the [100]-direction. If stretching along the [001]-direction, however, the BGs of 2 H-SiC shows a maximum value at \(\epsilon =0.03\). The BGs of 4 H-SiC and 6 H-SiC diminish if amplify tensile strain along the [001]-direction. In the case of 3C-SiC, the BGs shrinkages along with the compressing strain intensifying and vanishes finally at \(\epsilon =0.1\) in the [001] and [110]-directions, and in both [001] and [110]-directions the evolution is almost identical and changing linearly. In contrast, the BGs decreases much faster along the [110]-direction compared to the [001]-direction under tensile strain, that disappearing as \(\epsilon =0.12\) in the [110]-direction and \(\epsilon =0.29\) in the [001]-direction. We discuss in detail the mechanical properties and electronic structures evolutions under the strain of 2 H-, 4 H-, 3C-, and 6 H-SiC and expose that have the gigantic potential for practical and research value in valleytronics.