AUGER-ELECTRON-SPECTROSCOPY ANALYSIS OF CHEMICAL-STATES IN ION-BEAM-DEPOSITED CARBON LAYERS ON GRAPHITE

The mechanism of formation of diamondlike carbon layers at room temperature by ion-beam deposition has been investigated. Mass-selected C+ ions with kinetic energy between 50 and 150 eV were deposited on cleaved graphite under UHV conditions with a maximum dose of approximately 3 X 10(17) C+/cm2. Auger-electron spectroscopy (AES) was used to delineate the carbon chemical states that were formed. Similar experiments with a Ne+ ion beam revealed the extent of ion-induced defect formation. Factor analysis and least-squares fitting were applied for quantitative evaluation of the different carbon bonding states during film growth. A peak in the high-energy region of the KVV AES spectrum at 3.8 +/- 1 eV below the Auger line threshold is related to the degree of disorder in the different. carbon phases. The carbon-layer growth can be described as a two-stage process: First, the graphite lattice is being damaged; then an amorphous network of tetrahedrally (sp3) and trigonally (sp2) coordinated carbon atoms forms.