Adjustable effective electromechanical coupling of Lamb wave resonator using AlN/Sc0.096Al0.904N composite films

Abstract

With the rapid development of fifth-generation communication technology, there are more and more 5 G frequency bands and their bandwidths differ. Therefore, many researchers devote themselves to the study of resonators with adjustable electromechanical coupling coefficient. In this paper, we apply composite films to the Lamb wave resonator with a double-IDT configuration to achieve adjustable effective electromechanical coupling coefficient (Keff 2) of the first symmetric mode. The experimental results show that with the increase of the thickness ratio, the series resonant frequency ( fs ) of the resonator decreases from 2.567 GHz to 2.333 GHz; and the parallel resonant frequency ( fp ) of the resonator decreases from 2.608 GHz to 2.396 GHz. The Keff 2 is adjusted from 3.82% to 6.32% and the Δf ( fp−fs ) is adjusted from 41 to 63 MHz by using the AlN/Sc0.096Al0.904N composite films with different thickness ratios. This method may be an efficient way to adjust the bandwidth of the filter to meet the needs of different frequency bands.