Influence of inter-layer interactions and external stimuli on MX$_2$ (M= Mo/W, X= S/Se) heterobilayers

Understanding the inter-layer interactions in transition metal dichalcogenides (TMDs) based heterostructures plays a vital role owing to the symmetry of the structure, bandgap nature, and excitonic effects. In this present work, we have studied the structural and electronic properties of MX$_2$ (M= Mo/W, X= S/Se) heterobilayers using first-principles calculations based on density functional theory. Unlike the traditional homobilayers of TMDs, these heterobilayers result in broken inversion symmetry and alter their point group from D$_{3d}$ $\rightarrow$ C$_{3v}$. From the calculated Raman spectra of these heterobilayers, we have observed that the shear and layer breathing modes (LBM) at lower frequencies ($
11 pages, 6 figures