Reactions of xenon difluoride and atomic hydrogen at chemical vapour deposited diamond surfaces

X-ray photoelectron spectroscopy has been used to investigate the interacti on of xenon difluoride at chemical vapour deposited, polycrystalline diamon d surfaces. Dissociative chemisorption, resulting in the formation of adsor bed fluorine up to monolayer coverages, occurs on the clean surface with a sticking probability of approximately 10(-4). Prehydrogenation of the diamo nd, increases the initial reactive sticking probability, but reduces the sa turation fluorine coverage observed. Two forms of adsorbed fluorine are cle arly detected. The most thermally stable species, which is produced during initial xenon difluoride exposures, is attributed to covalently bonded carb on monofluoride functionalities. A second species, which is more weakly bou nd, has the characteristics of semi-ionic fluorine, which has been observed previously in the interaction of fluorine with other carbon forms. Thermal desorption studies show that the adsorbed fluorine desorbs over a large te mperature range (40-800 degreesC), reflecting the varying thermal stabiliti es of the differing populated states. Etching of a fluorine-saturated surfa ce with hydrogen atom fluxes shows two main regimes; initial rapid removal of the semi-ionic fluorine species, followed by the very slow abstraction o f covalent CF species. The comparative behaviour of the chemically vapour d eposited diamond films with diamond single crystal surfaces, with regard to the chemistry observed, is discussed. (C) 2001 Elsevier Science B.V. All r ights reserved.