Manipulation of electronic structure in WSe2 monolayer by strain

Abstract

Abstract In this paper, we study the electronic properties of WSe 2 monolayer with biaxial tensile strain and compressive strain by using first principles based on the density function theory. Under the biaxial tensile strain, WSe 2 monolayer retains direct band gap with increasing strain and the band gap of WSe 2 continuously decreases with increasing strain, eventually turn to metal when strain is equal to or more than 13%. Under the biaxial compressive strain, WSe 2 monolayer turns to indirect gap and the band gap continuously decreases with increasing strain, finally turn to metal when strain is up to −7%. The strain can reduce the band gap of the WSe 2 monolayer regardless of the strain direction. By comparison, we can see that the tensile strain appears to be more effective in reducing the band gap of pristine WSe 2 monolayer than the compressive strain from −5% to 5%. But the band gap turns to zero quickly from −6% to −7% under compressive strain, however for tensile strain from 5% to 13%, the band gap decreases slowly. Based on the further analysis of the projected charge density for WSe 2 monolayer, the fundamental reason of the change of band structure under biaxial tensile strain is revealed.