Effects of Crystallite Orientation on the Oxidation of MoS2 Thin Films.
Abstract
Thin films of MoS2 have been prepared, by rf sputter deposition, with different microstructures that show markedly different susceptibilities to oxidation or other environmental degradation. The films were exposed to air atmospheres of variable relative humidity, and the extent of oxidation was measured by means of Auger electron (AES) and X-ray photoelectron (XPS) spectroscopies. The morphologies of the films were determined by transmission electron microscopy. Depths of oxidation of the thin films were calculated from changes in AES peak-to-peak height ratios and in XPS peak intensity ratios through the use of standard escape-depth models for attenuation of electron emission by a layer of reacted material (in the present case, MoO3). The results show that MoS2 films whose crystallites are oriented with their basal planes at random angles to the plane of the substrate surface (designated Type I films) are oxidized to depths equal to or greater than 300 A, whereas films whose crystallite basal planes are coplanar with (parallel to) the substrate surface (Type II films) are oxidized to a maximum depth of 10 to 15 A. These results are interpreted in terms of relative reactivities of edge versus basal planes of the MoS2 crystallites. Keywords: Molybdenum disulfide; Solid lubrication; Thin-film chemistry; Thin-film oxidation; Crystallite orientation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 09, 1985
- Accession Number
- ADA160617
Entities
People
- P. D. Fleischauer
- T. B. Stewart
Organizations
- The Aerospace Corporation