Characterisation of nanostructured ZrO2 thin films formed by DC reactive magnetron sputtering

Abstract

Zirconium oxide (ZrO2) is also known as zirconia a promising material because of its high transparency, thermal stability and mechanical strength. Zirconium oxide with tetragonal structure show high strength and fracture toughness. Because of these reasons, zirconium oxide ceramics received much interest for tribological applications in human artificial joints. Main requirement for an artificial orthopaedic material is good binding with living bones through a formation of a biologically active bone like layer on its surface.1 It is an excellent biomaterial used as clinical application as heads of total hip prostheses by the combination of high molecular weight polyethylene cup sockets.2 It is also used in the fabrication of high strength core for dental implants due to its transparency.3,4 Zirconium ceramics find potential for toughening and strengthening of brittle hydro-oxyapatite and bioglass in biomedical applications.5,6 It has recognised as possible high-k dielectric candidate as an alternate to conventional silicon dioxide as gate dielectric in the next generation of complementary metal oxide semiconductor (CMOS) devices due to its moderate dielectric constant.7 High refractive index and wide optical band gap find it as active opto electron devices, high power laser and light emitting diodes.8 ZrO2 in thin film form also used as photon conductor in electro chromic devices9 and oxygen gas sensor.10 Various deposition methods namely thermal oxidation of zirconium films, electron beam evaporation, pulsed laser deposition, DC / RF magnetron sputtering, sol-gel process and spray pyrolysis were employed for preparation of ZrO2 thin films. 11–15 In this investigation, an attempt is made in the deposition of tetragonal structured and transparent ZrO2 thin films by DC reactive magnetron sputtering technique. The as-deposited ZrO2 thin films were annealed in air at a fixed temperature of 450oC for an hour. The as-deposited and annealed ZrO2 films were characterized for their chemical composition, crystallographic structure and optical properties and reported the results. Materials and methods