Evaluation of BAW and SAW Properties of (K, Na)NbO3 Thin Films Deposited by RF Sputtering

In this study, the BAW and SAW properties of (001)-oriented (K, Na)NbO
3
(KNN) thin films deposited using an RF magnetron sputtering system were evaluated to investigate the applicability of such thin films to high-frequency devices. As a result, a longitudinal wave phase velocity of 7,850 m/s and an electromechanical coupling coefficient of 7.4% were obtained. From the measured SAW properties, the responses of the zeroth and first modes of the Rayleigh-type SAW were observed. For the zeroth mode, a propagation loss of
$0.13\ \text{dB}/\lambda (\lambda$
: wavelength) and a frequency temperature coefficient of −41.5 ppm/°C were obtained.