Band gap engineering of 2H-MX2 (M = Mo; X = S, Se, Te) monolayers using strain effect

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted wide attention among researchers due to their extraordinary properties similar to graphene. In the present work, we have studied the electronic structure of 2H-MX2 (M = Mo; X = S, Se, Te) monolayer using density functional theory implanted in SIESTA Code. The calculated band structure shows the direct bandgap at the K point for all the MX2 monolayers and have values 1.56 eV, 1.38 eV, 0.98 eV for MoS2, MoSe2, MoTe2, respectively. We have carried out the systematic uniaxial tensile mechanical strain effect on the bandgap of monolayers in the range of −10% to + 10%. This systematic uniaxial tensile mechanical stain decreases the energy gap for all monolayers as we increase the strain from 0% to 10%. The strain variation from 0 to −10% yields varying bandgap, which firstly increases and then decreases with strain. Hence, we find that the application of strain could modulate the properties which forms the broken gap heterostructures within the 2H class.