Frictional properties of electron beam-deposited a-C:Si films

Abstract

Most films are deposited by chemical vapor deposition, but further expansion of their applications demands their fabricability by physical vapor deposition. In this study, hydrogen-free Si-incorporated diamond-like carbon (a-C:Si) films, which exhibit a low friction coefficient in air, were fabricated by electron beam deposition, and their hardness and frictional properties were investigated. a-C and a-C:Si films with Si contents of 5 and 15 at.% were deposited at substrate temperatures of 200, 300, and 500 °C. The ID/IG ratios calculated from the Raman spectra of the films tended to increase with increasing Si content and higher substrate temperature. a-C:Si with low Si content exhibited a hardness of only 10–20 GPa, similar to that of a-C, while a-C:Si with high Si content exhibited a hardness above 25 GPa when deposited at a substrate temperature of 200 or 300 °C. The friction coefficient of a-C:Si with high Si content was as low as 0.07–0.09. In sum, a-C:Si film with high Si content deposited at low substrate temperature without ion bombardment showed high hardness and low friction.