Primary study of structures of r.f.-sputtered MoS 2 films

Abstract

The composition and structures of r.f.-sputtered MoS 2 films have been determined by X-ray diffractometry (XRD), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and laser Raman spectroscopy (LRS). The r.f.-sputtered films were deposited on 440 C stainless steel substrate temperature control. We conducted XRD and LRS studies of approximately 0.8 μm thick r.f. sputter deposited MoS 2 fils to determine the structure, finding that the crystal raction of the films has a hexagonal layer structure with a distorted unit cell having a greatly elongated c 0 axis and a rather compressed a 0 axis which differ from those of the ordinary 2H-MoS 2. The concentrations of the surface and bulk atom species were determined by XPS and AES with depth profiling; the S:Mo atom ratio was found to be in the range 1.8–9, and certain amounts of oxygen are present in the bulk film. The XPS study was focused on the role of oxygen in the films, which differs from that of both the MoS 2 powder and target. This indicates that there is mainly non-chemisorbed oxygen in the films, where some oxygen atoms were probably substituted into the sulphur sites in the films to form an MoSO solid solution. Discussion of the mechanism of film growth and the orientation of the crystal fraction, which is primarily considered as a solid solution, and its crystallite sized related to lubrication are included.