Hydrogen incorporation and its structural effect on a-C : H films deposited by magnetron sputtering

Films of a-C:H have been prepared by de magnetron sputtering from a graphit e target with various ratios R of flow rates, or pressures, of H to Ar plus H in the chamber. In the analysis of the infrared (IR) spectra of a set of films with R varying from 2.5 x 10(-5) to 0.9, features characteristic of vibrational modes associated with H bonded in a variety of configurations, namely sp(2) and sp(3) sites involving single-, double- or (in the case of sp(3) sites) triple-bonded H, are detected. The relative fractions of the d ifferent sites do not change with R up to about 0.1 but, for larger R, the fraction of sp(3)C sites bonded to a single H atom increases and the other configurations decrease. At the same time the linewidths of the peaks contr ibuting to the overall spectra increase with R, which we suggest is due to increased stress in the films. (C) 2000 Published by Elsevier Science B.V. All rights reserved.