NSPUDT using c-axis tilted ScAlN thin film

This paper reports finding of directionality in the 44% Scandium doped Aluminum Nitride thin film based surface acoustic wave devices. Some previously reported SAW devices using bulk substrates showed higher power of acoustic signals in either forward or backward direction depending on their crystal orientations and are called natural single-phase unidirectional transducers (NSPUDT). As these reports were based on bulk substrates, for the first time, we report NSPUDT using c-axis tilted Scandium doped Aluminum Nitride thin film SAW devices on sapphire. In addition, we also examined the c-axis tilt dependency to improve transducers return loss. It is worth to put in notice here that our observance of directionality is specifically in sezawa wave. Hence, the comparison for both acoustic waves i.e. Rayleigh and Sezawa is also reported.