文摘
MoS2 thin films have been achieved on molybdenum, tantalum and tungsten substrates. The films were obtained by solid state reaction between the constituents in thin film form, the substrates being coated by a thin Ni layer. Multilayer samples Mo/S/Mo–Mo/S were annealed under argon flow at T = 1073 K or 1123 K for 30 min. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). All films are nearly stoichoimetric and crystallized in the expected 2H-MoS2 structure. (XPS analysis confirms the stoichoimetry and the small contamination of the films while Ni was detected at the surface of the samples). The films are polycrystalline but the size and the orientation of the crystallites depend on the substrates. While in the case of tungsten substrates the crystallite size reach the total thickness of the film (≥100 nm) and are highly oriented with their c-axis perpendicular to the plane of the substrate, in the case of the other refractory metals (Ta, Mo), their size is smaller and the texture of the films is not so good. These differences are explained by the influence of the crystalline properties of the substrates on the growth process of MoS2 thin films. The current–voltage characteristic of the W/Ni/MoS2/W structure show that an ohmic contact is obtained.
