Influence of process gas and deposition energy on the atomic and electronic structure of diamond-like (a-C:H) films

Abstract

Amorphous hydrogenated carbon films (a-C:H) were prepared by means of direct ion beam deposition (IBD) and using different process gases. The films were characterized by in situ electron spectroscopy. In the case of methane, typical a-C:H valence band (VB) spectra were obtained over a very large range of deposition energies. However, the VB spectra of films prepared from benzene revealed a distinct change when deposited with energies below 305 eV which can be interpreted in terms of a considerably higher amount of sp 2 bonds or a higher degree of aromaticity. Using styrene as a process gas, even at a deposition energy of 1000 eV, the VB spectra clearly indicate structural differences compared to a-C:H.