A complementary study of bonding and electronic structure of amorphous carbon films by electron spectroscopy and optical techniques

A complementary study of composition and bonding of sputtered a-C films, de posited on Si(001) substrates with various bias voltages (V-b) applied to t he substrate during deposition is presented. The sp(3) and sp(3) fractions in the films were calculated by deconvolution of the X-ray photoelectron sp ectroscopy (XPS) Cls peak and studied by the differential auger electron sp ectroscopy (AES) C1s peak signal. The results of this analysis are compared with the estimation of sp(3) fraction calculated by spectroscopic ellipsom etry (SE) and validated using density measurements by X-ray reflectivity. I t was observed a considerable increase of sp(3) content in films deposited with negative V-b. The respective sp(3) and sp(2) fractions and Ar concentr ation with respect to the V-b and the depth profile analysis give valuable information on the deposition mechanism of the sputtered a-C films. XPS val ence band spectra provided the electron density of states in the a-C films' valence band. The characteristic broad p band of diamond was prominent in most of the films. The valence band structure of the films was correlated w ith their optical response measured by SE. (C) 2001 Elsevier Science B.V. A ll rights reserved.