Growth of LiNbO3 thin films by bias sputtering

Interest in the use of LiNbO₃ thin films for piezoelectric and optical applications has increased. However it has been very difficult to prepare high-quality LiNbO₃ films. In order to improve the quality, LiNbO₃ films were prepared by bias sputtering, and the effects of bias electric field during the LiNbO ₃ sputtering deposition were investigated. The deposition rate and Li/Nb composition of obtained films were greatly influenced by the bias field applied externally. The relationship between the bias voltage, the deposition rate and the composition was evaluated, revealing that both the rate and Li composition of the films were decreased at negative bias voltage. The oriented LiNbO₃ films on SiO₂/Si substrates may show fine piezoelectric and electric properties. However it has been very hard to grow oriented LiNbO₃ films on SiO₂. C-axis oriented LiNbO₃ films were successfully obtained on SiO₂/Si by bias sputtering. The as-grown oriented films also showed pyroelectricity. It was revealed that bias sputtering was very useful in the improvement of the crystallinity of LiNbO₃ films