Factor analysis applied to carbon Auger spectra of tungsten carbide coatings deposited by reactive sputtering

Abstract Factor analysis is applied to the d(NE) dE Auger electron spectra of a series of magnetron sputtered tungsten carbide films which were deposited at different reactive gas flows. This method of data evaluation enables the type of the chemical bonding of carbon (carbidic or graphitic) to be recognized and the respective concentration to be evaluated. It is shown that reactive sputtering of a pure tungsten target with an admixture of about 3 mol% C 2 H 2 to the working gas (Ar) yields stoichiometric WC films. The carbon components of these films are found to be mainly bonded in carbidic form. An increasing admixture of reactive gas leads to an increasing deposition of carbon in its graphitic form. If films are deposited by non-reactive sputtering of a tungsten carbide target the carbidic component of the film is depleted due to preferential sputtering effects. It is shown that this depletion can be compensated by the admixture of C 2 H 2 to the working gas. Furthermore, it is investigated how the electron bombardment affects the chemical bonding state of a tungsten carbide surface.