Effects of the in-plane uniaxial and biaxial strains on the structural and electronic properties of the monolayer ZrS2: A first-principles investigation

Abstract

The effects of in-plane uniaxial strain along both armchair direction and zigzag direction as well as symmetrical biaxial strain on the structural and electronic properties of the monolayer ZrS2 have been investigated by using first-principles calculations. It is found that firstly different from the bulk materials, the band gap type of the monolayer ZrS2 at zero strain depends on the odd (even) nature of the selected supercell, i.e. an indirect (direct) band gap is obtained for odd (even) supercell. Second, for three strain schemes the band gap value of the monolayer ZrS2 decreases quickly with increasing compressive strain but increases firstly to the maximum value and then decreases with increasing tensile strain mainly resulted from the variation of the conduction band minimum, and the compressive strain is more effective than the tensile strain in band gap engineering. Thirdly, under biaxial strain the indirect band gap of the monolayer ZrS2 increases from 0.00 eV (metal) at -10% compressive strain to the maximum value of 1.616 eV at 6% tensile strain and then decreases. Fourth, when a uniaxial strain is applied to the monolayer ZrS2 along either armchair or zigzag direction a direct to indirect band gap transition is observed at -10% compressive strain.