XPS study of sputtered alumina thin films

Alumina thin films were deposited on SS304 and Ti metal substrates using a pulsed rf magnetron sputtering technique at different radio frequency (rf) powers corresponding to input powers of 300, 500 and 700 W. Both direct and reactive sputtering methods were employed to deposit the alumina films. The deposited films were thoroughly characterized by X-ray photoelectron spectroscopy (XPS) to investigate electronic structure and stoichiometry. Further, the effect of different rf powers, role of substrates and effect of deposition methods e.g. direct and reactive sputtering on binding energy, atomic concentration ratio (e.g., oxygen to aluminium ratio, O/Al) and related properties have been studied extensively by XPS. The results suggested that the reactive sputtering method could provide alumina thin films with the chemical composition that matches with the stoichiometric one. Further, the film deposition process by reactive sputtering was not a sensitive function of the variations in the input power.