Analysis of the electronic structure of hydrogenated amorphous carbon via Auger spectroscopy

The X-ray excited Auger electron spectroscopy (XAES) has been used to investigate the pa electronic structure of hydrogenated amorphous carbon (a-C:H) films, at different hydrogen content. The X-my Photoelectron Spectra (XPS) of the Cls core level with the associated photoelectron energy loss spectrum (PELS) have been recorded simultaneously to the XAES data. It has been proved that the double-differentiated p pi*p pi Auger self-fold contribution to the CKVV Auger spectrum is very sensitive to the hydrogen content and/or sample preparation conditions, providing a reliable fingerprint of the material. The extent of the electronic gap and the fraction of sp(2) sites of the a-C:H films have been estimated. The features of the Auger p pi*p pi self-fold structure can be associated to those appearing in the electronic density of states evaluated using Molecular Dynamics simulations. (C) 1999 Elsevier Science B.V. All rights reserved.