Strain engineering and lattice vibration manipulation of atomically thin TaS₂ films

Beside the extraordinary structural, mechanical and physical properties of two-dimensional (2D) materials, the capability to tune properties via strain engineering has shown great potential for nano-electromechanical systems. External strain, in a controlled manner, can manipulate the optical and electronic properties of the 2D materials. We observed the lattice vibration modulation in strained mono- and few-layer tantalum sulfide (TaS₂). Two Raman modes, E_1g and E¹ _2g, exhibit sensitive strain dependence, with the frequency of the former intensity increasing and the latter decreasing under a compressive strain. The opposite direction of the intensity shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to strain-induced competition between the electron-phonon interlayer coupling and possible stacking-induced changes of the intralayer transport. Our results enrich the understanding of the lattice vibration of TaS₂ and point to strain engineering as a powerful tool for tuning the electron-phonon coupling of 2D materials.