Thin films of the metallic oxide have a wide variety of applications such as surface acoustic wave devices (SAW), bulk acoustic wave devices (BAW), acoustic-optic devices, micro-electromechanical systems (MEMS), band pass filters, optical wave-guide, and laser deflectors using piezoelectric or piezooptic properties. With appropriate dopants such as aluminium, some of the oxides are electrically conductive and could be employed as transparent conducting electrodes for flat panel displays and solar cells. Due to their unique conducting mechanism based on oxygen vacancies, the oxides are also used in oxygen gas sensors, window layers in copper indium diselenide based heterojunction solar cells, and high temperature solid lubricants in gas turbine engines, and in electro chromic devices. Conducting metal oxide thin films are good infrared detectors, reflectors and are applied as energy efficient window treatments where high infrared reflectance and low thermal emittance are required.