Electron spectroscopy study of hydrogenated amorphous carbon films formed by methane ion beam deposition

Abstract

We studied the electronic structure of hydrogenated amorphous carbon films (HACFs) by UV photoelectron spectroscopy, X-ray photoelectron spectroscopy and Auger electron spectroscopy. The valence band spectra are similar to those obtained from measurements of the (111) surface of crystalline diamond. The work function of the HACFs increases, and the Fermi edge moves toward the valence band edge, as the annealing temperature increases ( T ⩾ 400 °C). The secondary electron spectra and the C KVV Auger peaks of HACFs and graphite differ appreciably. The C 1s loss spectrum is very sensitive to the chemical environment of the carbon atoms and directly reflects the change from an essentially fourfold-coordinated carbon network to a more graphitic structure for annealing temperatures above about 500 °C.