Impact of strain on the electronic, phonon, and optical properties of monolayer transition metal dichalcogenides XTe <sub>2</sub> (X = Mo and W)
Md. Rasidul Islam, Md. Rayid Hasan Mojumder, Biazid Kabir Moghal, A. S. M. Jannatul Islam, Mohammad Raza Miah, Sourav Roy, Anuj Kumar, ASM Shihavuddin, Ratil H. Ashique
Abstract
Abstract Here, we provide a systematic assessment of biaxial strain effects on the electronic, phonon, and optical properties of monolayer transition metal dichalcogenides (TMDs) XTe 2 (X = Mo and W) using density functional theory calculations. We observed a large direct bandgap of 1.163 eV and 0.974 eV for MoTe 2 and WTe 2, which reduced to 1.042 eV and 0.824 eV in the spin–orbit coupling ambient. The XTe 2 structures show a tunable bandgap with the variation of the applied biaxial strains. Due to the breaking of inversion symmetry, a large spin-valley coupling emerged at the valance band edges for both MoTe 2 and WTe 2 monolayers under applied biaxial strain. The phonon properties with different biaxial strains reveal that monolayer MoTe 2 is more stable than the WTe 2 structure. The calculated optical properties demonstrate that the dielectric constant and absorption coefficient of MoTe 2 and WTe 2 move to higher photon frequencies when the compressive strain is increased. On the other hand, with the increase in tensile strain, a red-shift behavior is found in the calculated optical properties, indicating the suitability of the XTe 2 monolayer for different infrared and visible light optical applications.