Ultrahigh-Vacuum High-Resolution Transmission Electron Microscopy of Sputter-Deposited MoSsub2 Thin Films.
Abstract
High-resolution electron microscopy has been used to characterize the structure of sputter-deposited MoS2 coatings under both conventional and ultrahigh-vacuum (UHV) conditions. As deposited, the films have a mixture of short-range ordered basal-plane and edge-plane oriented grains near the film substrate interface; structural changes were characterized in a UHV transmission electron microscope as a function of two processing variables: temperature and Au deposition. Annealing in an oxygen environment was also carried out to assess chemical stability. During thermal annealing in UHV and in oxygen, substantial long-range ordering of the basal islands followed by grain growth was observed. Inhomogeneous oxidation resulting in the formation of MoO3 in the initial stages followed by grain growth, yielding the final morphology of a mixture of MoO3 crystallites of 5-50 nm size was seen on annealing in an oxidizing atmosphere. Au nucleation and growth on both thermally annealed and as-deposited films were seen to follow the Volmer-Weber mode. i.e., three-dimensional islands; these islands were also seen to be highly textured. Also, in comparison with carbon and SiO substrates, Au demonstrated higher stability to electron beam fluxes on MoS2, suggesting higher bonding strengths to the substrate. These experiments demonstrated the paramount need for UHv conditions during both deposition and characterization to avoid uncertain contamination artifacts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1995
- Accession Number
- ADA301917
Entities
People
- G. Jayaram
- Laurence D. Marks
- M. R. Hilton
- N. Doraiswamy
Organizations
- The Aerospace Corporation