Effect of Alumina Film on Surface Acoustic Wave Properties of ZnO Thin Film Surface Acoustic Wave Devices

Abstract

ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on interdigital transducers (IDTs)/Al 2 O 3 /glass substrates. The alumina films were deposited on glass substrates by electron beam evaporation. The phase velocity, coupling coefficient and temperature coefficient of frequency (TCF) of SAW device were increased when we increased the thickness of alumina film. The experimental result is beneficial to upgrade the performance of the ZnO thin film SAW devices on cheap glass substrate.

Effect of Alumina Film on the Surface Acoustic Wave Properties of Crystalline Quartz and Lithium Niobate

“…In our previous study, the phase velocity of a SAW device with an 8-m-thick alumina film was measured to be about 4733 m/s, which is 89.6% that in the case of ZnO/sapphire (5283 m/s). 23) The observed increase in the SAW velocity in our Al 2 O 3 /LiNbO 3 samples is attributed to the high stiffness of the Al 2 O 3 films deposited on the LiNbO 3 substrate. The Young's moduli of a densely sintered conventional polycrystalline alumina film and a LiNbO 3 substrate are 350-400 24) and 166-181 GPa, 25) respectively, thereby verifying the observed increase in stiffness.…”

“…In our previous study, we investigated the SAW properties of ZnO/Al 2 O 3 /Si layered SAW devices. 23) The experimental results (including phase velocity, coupling coefficient, and TCF) approached those of ZnO/sapphire when we increased the thickness of the alumina film.…”

Improvement of surface acoustic wave characteristics of ZnO film/interdigital transducer/glass substrate using alumina film interlayer

“…However, high-frequency ZnO thin-film SAW devices on glass substrates have great merit owing to their lower cost. [18][19][20][21][22][23] In our previous study, we studied the SAW properties of ZnO/Al 2 O 3 /Si layered SAW devices 26,27) to determine an alternative of a sapphire substrate for highfrequency SAW device applications. In addition, the obtained results could also be useful for integrating a semiconductor and high-frequency SAW devices on the same Si substrate.…”