High frequency 9 GHz third hamonic surface acoustic wave resonator with grooved Al electrodes in LiNbO₃

Abstract Due to power handling limitations, the wavelength of interdigital transducers (IDTs) in surface acoustic wave (SAW) devices must be 1.2 μm or longer. Consequently, the exciting frequency of SAW devices on standard 42°YX LiTaO 3 (LT) substrates is typically limited to around 3 GHz. Developing SAW devices for the 7–24 GHz frequency range (FR3), as specified in the 3GPP standards, poses significant challenges. In this study, finite element method simulations demonstrated that embedding the IDT in LiNbO 3 (LN) and LT substrates enables the excitation of high-frequency. Based on these findings, we fabricated grooved Al IDTs with a wavelength of 1.2 μm in a 26°YX LN substrate. This successfully excited a high frequency 9 GHz third harmonic SAW, achieving a frequency 2.3 times higher than the fundamental SAW and 2.8 times that of a standard SAW device using a 42°YX LT substrate.