Highly Conductive and Optically Transparent Polycrystalline Iridium Oxide Thin Films Grown by Reactive Pulsed Laser Deposition

ABSTRACTReactive pulsed laser deposition has been used to deposit IrO2 thin films on both SiO2 and fused quartz substrates, by ablating a metal iridium target in oxygen atmosphere. At a KrF laser intensity of about 1.7 × 109 W/cm2, IrO2 films were deposited at substrate deposition temperatures ranging from room-temperature to 700 °C under an optimum oxygen ambient pressure of 200 mTorr. The structure, morphology, electrical resistivity and optical transmission of the deposited films were characterized as a function of their deposition temperature (Td). High quality IrO2 films are obtained in the 400–600 °C deposition temperature range. They are polycrystalline with preferred orientations, depending on the substrate, and show a dense granular morphology. At a Td as low as 400 °C, highly conductive IrO2 films with room-temperature resistivities as low as (42±6) μΩ cm are obtained. Over the 300–600 °C Td range, the IrO2 films were found to exhibit a maximum optical transmission at 450 °C (∼ 45 % at 500 nm for 80 nm-thick films).