Application of Thin Piezoelectric Films in Diamond-Based Acoustoelectronic Devices

Abstract

The theory of external loading influence on acoustic parameters of piezoelectric five- layered structure as “Al/(001) AlN/Mo/(001) diamond/Me” has been developed. Oscilla- tions in diamond-based high-overtone bulk acoustic resonators (HBARs) have been inves- tigated in terms of 3D FEM simulation. Peculiarities of technology of aluminum-scandium nitride (ASN) films have been discussed. Composition Al0.8Sc0.2N was obtained to create the diamond-based HBAR and SAWresonator. Application of ASN films has resulted in a drastic increasing an electromechanical coupling up to 2.5 times in comparison with aluminum nitride. Development of ASN technology in a way of producing a number of compositions with the better piezoelectric properties has a clear prospective. SAWresona- tor based on “Al IDT/(001) AlN/(001) diamond” structure has been investigated in the band 400–1500 MHz. The highest-quality factor Q ≈ 1050 was observed for the Sezawa mode at 1412 MHz. Method of measuring HBAR’s parameters within 4–400 K at 0.5–5 GHz has been developed. Results on temperature dependence of diamond’s Q- factor at relatively low frequencies were quite different in comparison with the ones at the frequencies up to 5 GHz. Difference could be explained in terms of changing mecha- nism of acoustic attenuation from Akhiezer’s type to the Landau-Rumer’s one at higher frequencies