Peculiarities of the Acoustic Wave Propagation in Diamond-Based Multilayer Piezoelectric Structures as Me1/(Al,Sc)N/Me2/(100) Diamond/Me3 and Me1/AlN/Me2/(100) Diamond/Me3 under Metal Thin-Film Deposition

New theoretical and experimental results of microwave acoustic wave propagation in diamond-based multilayer piezoelectric structures (MPS) as Me1/(Al,Sc)N/Me2/(100) diamond/Me3 and Me1/AlN/Me2/(100) diamond/Me3 under three metal film depositions, including the change in the quality factor Q as a result of Me3 impact, were obtained. Further development of our earlier studies was motivated by the necessity of creating a sensor model based on the above fifth layered MPS and its in-depth study using the finite element method (FEM). Experimental results on the change in operational checkpoint frequencies and quality factors under the effect of film deposition are in satisfactory accordance with FEM data. The relatively small decrease in the quality factor of diamond-based high overtone bulk acoustic resonator (HBAR) under the metal layer effect observed in a wide microwave band could be qualified as an important result. Changes in operational resonant frequencies vs. film thickness were found to have sufficient distinctions. This fact can be quite explained in terms of the difference between acoustic impedances of diamond and deposited metal films.

Automated summary

This study investigates the propagation of microwave acoustic waves in various diamond-based piezoelectric structures and observes the change in quality factor under metal film deposition. The experimental results are in accordance with the finite element method data. The study finds that the diamond-based high overtone bulk acoustic resonator shows a relatively small decrease in quality factor under the effect of metal layers in a wide microwave band, which is an important finding. Additionally, the operational resonant frequencies also vary with film thickness, which can be explained by the difference in acoustic impedances between diamond and metal films.