Growth of lithium tantalate thin films by radio-frequency magnetron sputtering with lithium enriched target

LiTaO3 thin films were deposited by radio-frequency magnetron sputtering with a Li enriched target composed of Li2O2/Ta2O5 (55:45 at.%). Morphology, crystallinity, dielectric and pyrolectric properties of thin films of LiTaO3 are studied according to the temperature of deposition and the nature of the back electrode (Ru/RuO2 and RuO2). In order to develop thermal microsensors containing pyrolectric thin layers deposited on membranes of SiNx ensuring the thermal isolation of the device, the final aim is to improve the pyroelectric coefficient for infrared pyroelectric detectors applications. The best pyroelectric coefficient of LiTaO3 thin films (400 nm), obtained for a growth temperature of 620 °C and a pressure of 0.67 Pa, is equal to 40 µC/m2 K.