Post deposition excimer laser processing of MoSx thin films

Abstract

We have examined the effect of excimer laser surface processing and doping with Au on the mechanical, tribological, and bonding properties of MoS_x thin films. We find that the effects of processing are manifested primarily in the surface of the films, but that there is also some film-substrate interaction during high fluence processing. The changes are sufficient to dramatically alter the wear life of the films. At low loads, laser processing alone reduces the run-in period and increases wear life. At higher loads, processing reduces wear life, although the run-in period is still short. These results are understood in terms of changes in the hardness of the surface of the films. Laser processing renders deposited films insensitive to high humidity storage. After laser processing, Raman spectroscopy shows changes in bonding to that characteristic of single crystal MoS₂. Laser doping with Au results in wear life comparable to or greater than that of unprocessed films even at the highest loads used. Thus, laser doped MoS_x films show lower initial friction, comparable wear life, and may exhibit greater environmental stability than as-deposited films.