Correlation between process conditions, chemical composition and morphology of MoS₂films prepared by RF planar magnetron sputtering

MoS 2 films have been prepared by RF sputtering in a planar magnetron system. Their chemical composition was analysed by energy dispersive X-ray spectroscopy. The morphology and growth characteristics were examined by scanning and transmission electron microscopy and by electron diffraction. Correlation between process conditions, film stoichiometry and morphology has been pointed out by a systematic variation of the experimental sputter parameters with emphasis on a stable substrate temperature during deposition. It has been shown that by a precise control of the substrate temperature specific morphologies can be obtained which are independent of film thickness. In particular, at high deposition temperature the films exhibit a lamellar-type microstructure with the 002 planes of the MoS 2 crystallites perpendicular to the substrate. The crystallite size strongly decreases for deposition at lower temperature. The increase of power density was found to give higher sulphur concentration in the films whereas substrate biasing results in a pronounced excess of the metallic element.