Strain effect on mexican-hat dispersion and electronic band gap of 2D α-CN

Abstract

Two dimensional α-CN material with Mexican-hat-shaped quartic dispersions and its valence band edge position with respect to with redox potential of water makes it a potential candidate for thermoelectric and hydrogen generation. However, the large indirect band gap of α-CN limits its efficiency in water splitting reaction. We used first principles calculations based on density functional theory to alter the band gap and analyze the quartic dispersion of valence band under biaxial strain. The electronic band gap decreases with increasing biaxial strain and improving its efficiency for water splitting. The electronic band gap of α-CN becomes suitable for UV light applications at 6-12% strain. The changes in Mexican-hat dispersion were analyzed by determining strain induced changes in the Mexican-hat coefficient. Valence band follows quartic dispersion preserving the Mexican-hat at VBM under compressive and tensile strains preserving the thermoelectric performance of α-CN.