Electron Spectroscopy of COx Magnetron Sputtered Films

Abstract

COx films were deposited by magnetron sputtering of a graphite target within two different routes: (i) by sputtering in an Ar+O2 gas mixture or (ii) by sputtering in pure Ar followed by annealing at 300 °C in air. Surface composition and chemical bonding was studied by X-ray induced photoelectron and Auger electron spectroscopy (XPS/XAES), and electron energy loss spectroscopy (EELS) in a low energy loss region. Oxygen content reached ∼20 at. % in the COx layers, independent on the route used. The C 1s spectral line shapes indicate C–O and C=O bonding states, regardless dominating C–C and CHx bonds. Substantial differences were found in the XAES and reflection electron energy loss spectra (REELS) recorded from surface regions of the samples. The both spectra indicate dominating sp2 bonding of carbon atoms in an analyzed volume of COx films sputtered in Ar and oxidized in air at elevated temperature whereas for those deposited in an Ar+O2 mixture the sp3 bonding prevails over sp2.