Composition and growth mode of MoSx sputtered films

MoSx lubricating thin films were deposited by nonreactive, reactive, and low energy ion‐assisted radio‐frequency (rf) magnetron sputtering from a MoS2 target. Depending on the total and reactive gas pressures, the film composition ranges between MoS0.7 and MoS2.8. A low working pressure was found to have effects similar to those of low‐energy ion irradiation. Films deposited at high pressure have (002) planes preferentially perpendicular to the substrate, whereas films deposited at low pressure or under low‐energy ion irradiation have (002) mainly parallel to it. Parallel films are sulfur deficient (MoS1.2−1.4). Their growth is explained in terms of an increased reactivity of the basal surfaces, itself a consequence of the creation of surface defects due to ion irradiation. The films exhibit a lubricating character for all compositions above MoS1.2. The longest lifetime in ball‐on‐disk wear test was found for MoS1.5.