Impact of device parameters on performance of one-port type SAW resonators on AlN/sapphire

Abstract

We have studied the impact of various device parameters including surface acoustic wavelength (λ), interdigital transducers (IDT) finger apertures (LIDT), number of reflector gratings (Nref), and reflector types on the performance of one-port type AlN based SAW resonators on sapphire systematically. Experimental results indicate that the acoustic velocity of 1 µm-AlN/sapphire bilayer structure is 5536 m s−1, 60% higher than that of LiNbO3 when λ is 8 µm. For 1 µm-AlN/sapphire bilayer structure, resonators with λ of 8 µm exhibit better performance than that of resonators with λ of 12 µm and 16 µm, with an electromechanical coupling coefficient () of 0.168%, and S11 magnitude difference at resonant and anti-resonant frequency (ΔS11) of 0.42 dB. Both ΔS11 and of resonators will increase sharply with the increase of LIDT from 80 µm to 240 µm, exhibiting 140% and 150% improvement, respectively. The of resonators will increase 38% with the increase of Nref from 100 to 300. The impact of reflector types including open-circuited and short-circuited reflectors on performance of resonators is not obvious.