Layer-dependent electronic and vibrational properties of SnSe$_{2}$ and SnS$_{2}$ 2D materials

Layered metal chalcogenides possess a wide range of unique electronic properties, which are currently explored for applications as novel two-dimensional electronic materials. SnS$_{2}$ and SnSe$_{2}$ layered materials consist of covalently bonded S-Se-S (Sn-Se-Sn) sheets bonded together by weak van der Waals interactions. The atomic, electronic and vibrational properties of SnS$_{2}$ and SnSe$_{2}$ thin films are investigated using first-principles density functional theory. The evolution of the thickness-dependent band structure and Raman spectra are discussed, as well as the effects of strain and the influence of the substrate. The first-principles results are compared with available experimental data.