Fine structures of valence-band, x-ray-excited Auger electron, and plasmon energy loss spectra of diamondlike carbon films obtained using x-ray photoelectron spectroscopy

Abstract

The electronic structures of diamond and graphite using x-ray photoelectron spectroscopy (XPS) are compared to that of diamondlike carbon (DLC) films that were deposited using unbalanced magnetron sputtering. High resolution spectra were obtained for the XPS valence-band, x-ray-excited Auger electron (XAES), and photoelectron energy loss. The electronic structures of DLC films are discussed as a function of argon gas pressure and the results are in good agreement with the optical band gap measurement. The XAES spectra from diamond, DLC, and graphite samples show noticeable differences. The XAES N(E) spectra from DLC films contain four carbon KLL transition peaks. The features of the XAES spectra of DLC films are similar to diamond and do not show a graphitelike shoulder. The DLC films deposited at low argon gas pressure show evidence of diamondlike fine structure in the valence-band and photoelectron energy loss spectra, and have wider optical band gaps.