Regulation of monolayer MgGeN2 thin film with uniaxial and biaxial strain

Abstract

The regulation of electronic and optical properties with uniaxial and biaxial strain is computationally investigated for the monolayer thin film of a newly discovered quasi-layered MgGeN2 phase. It is found that, under uniaxial compression in both [100] and [010] directions with the perpendicular lattice parameter relaxable, the band gap will first increases and then decreases, while under uniaxial tensile strain the band gap decreases monotonically and the light absorption in the visible region is strongly enhanced. When uniaxial compression was applied with the perpendicular lattice constant fixed, the band gap behaves like the first kind of uniaxial compression and the light absorption is enhanced in visible range by compression. When biaxial strain was applied, the band gap shows a monotonic decrease from the largest compression down to the largest tensile strain, while the light absorption behaves in the opposite way. Therefore, the band structure and light absorption of monolayer MgGeN2 can be efficiently tuned with strain and stress, which can potentially be used for the MgGeN2 film in device design, thus promoting its applications in optoelectronics and photocatalysis.