Crystalline structure of very hard tungsten carbide thin films obtained byreactive pulsed laser deposition

Very hard (H-upsilon congruent to 26 GPa), uniform and adherent tungsten ca rbide thin films were obtained by multipulse excimer laser ablation of tung sten targets in methane at (5 x 10(-2)-1) Pa pressure. The films were depos ited on substrates placed parallel to the target at a distance of 70 mm. In creases in the gas pressure result in an increase of the carbon content in the deposited films accompanied by a decrease of the mean WC crystallite si ze in the deposited layers. The microhardness of the films shows a nonlinea r evolution with the methane fill pressure with a maximum in excess of 26 G Pa at p = 1 x 10(-1) Pa. (C) 1999 American Vacuum Society. [S0734-2101(99)0 3901-9].