Direct current magnetron sputtering deposition of nanocomposite alumina — zirconia thin films

Mixed aluminium oxide–zirconium oxide thin solid films have been synthesized at ~ 300 °C by reactive direct current magnetron sputtering from two targets. Partial pressure control of the oxygen gas ensured stoichiometric films without compromising the deposition rate. The composition of the films ranged from pure alumina to pure zirconia as measured by X-ray photoelectron spectroscopy. Microstructural characterisation showed that the pure zirconium oxide films nucleated initially as the tetragonal zirconia phase, while the 100/010/001 textured monoclinic zirconia phase grew under steady-state conditions with a columnar structure. Addition of aluminium to ~ 3 at.% caused the formation of tetragonal zirconia in the films, while further additions led to an amorphous structure as governed by the alumina under the present kinetic limitations.