Strain engineering tuned vibrational dynamics of 2D transition metal dichalcogenide heterostructures: a first-principles investigation.

Abstract

Controlling vibrational modes and energy gap by creating van der Waals (vdW) heterostructures through strain engineering is a novel approach to tailor the vibrational and electronic properties of two-dimensional materials. Numerous theoretical and experimental studies have significantly contributed to analyzing the properties of transition metal dichalcogenides, known for their multifunctional applications. In this study, we investigate the strain and stacking dependent vibrational properties of WSe₂/MoSe₂and MoSe₂/WSe₂/MoSe₂vdW heterostructures usingfirst-principlesbased density functional theory calculations. The dynamical stability of all vdW heterostructures makes them feasible in fabrication. Our phonon calculations and zone center phonon modes analysis signify that the interlayer interaction influences interlayer breathing and shear phonon modes, which play an important role in thermal properties. The effect of strain engineering on the vibrational modes and energy gap of vdW heterostructures are further discussed. The tensile and compressive biaxial strain on the vdW heterostructures results in phonon softening and hardening, respectively.