Study of structural and electronic properties of few-layer MoS 2 film

Transition Metal Dichalcogenides (TMDs) such as MoS 2 are important 2D materials due to their attractive electronic, optical and, catalytic properties. Among its various applications, the MoS 2 based sensor development requires, preparation of thin film of MoS 2 at a large scale. In this paper, we are reporting the synthesis of few-layers MoS 2 films on SiO 2 /Si substrate using drop casting method. The MoS 2 films are characterized using Optical Microscopy, Atomic Force Microscopy, Raman Spectroscopy, X- Ray Diffraction, Transmission Electron Microscopy and, Photoluminescence (PL) techniques. The Raman and AFM measurements indicate that the samples with 9–11 layers (≈ 8 nm). The XRD pattern reveals the hexagonal structure (2H) of MoS 2 films. The observed (0 0 2) XRD peak at 2θ ≈ 14.4° corresponds to the interplanar spacing d (002) ≈ 6.14° A and lattice parameter c ≈ 12.28 °A. Hexagonal structure of grown film of MoS 2 and interplanar spacing d (002) are reconfirmed by the FFT of the HRTEM image. The observed band structure using UV–Vis and PL results are compared with Density Functional Theory (DFT) and Density of States (DOS) calculations show the indirect band nature of few-layers MoS 2 films. The calculated DOS and Partial Density of State (PDOS) plots show the formation of bands at different symmetry points due to atomic orbital interaction and the contribution of particular atoms and their orbitals. The obtained PL and UV–Vis spectra corresponding to the different energy levels are agreed with a calculated band gap at different symmetry points using DFT.