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

Abstract

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.

Microwave Diamond-Based HBAR as a Highly Sensitive Sensor for Multiple Applications: Acoustic Attenuation in the Mo Film

“…For a declared purpose, the "Al/Al 0.73 Sc 0.27 N/Mo/(100) diamond/Me" diamondbased multilayer piezoelectric structure (MPS), as a sensory device, was developed by a known technology using magnetron sputtering [20]. First, the conducting Mo layer was deposited onto a cleaned diamond surface.…”

“…It is important to highlight that the aluminum-scandium nitride Al 1-x Sc x N (ASN) piezoelectric film was provided with L-type acoustic wave excitation in a frequency band up to 40 GHz [15]. Earlier, diamond-based HBAR sensors using the "Me1/(Al,Sc)N/Me2/(100) diamond/Me3" and "Me1/AlN/Me2/(100) diamond/Me3" structures were applied to study the thin and ultrathin metal films such as Mo, Al, Sc, and Pt [17][18][19][20]. The thickness sensitivity under the Pt deposition was estimated as ±0.5 nm.…”

“…The studies in which HBARbased devices were applied as gravimetric sensors for solid films continued the works of Mansfeld [13]. In these works, the authors tried to increase the sensitivity by raising operational frequencies [20] up to 20 GHz, implementing different substrates and piezoelectric layers [14]. During these studies, a model for calculating frequency shifts with more precision than Sauerbrey's model was suggested.…”

A review of acoustofluidic separation of bioparticles

“…On the other hand, materials like silicon and glass with superior acoustic properties are more appropriate for channel fabrication (Safaee et al 2022 ; Karaman 2022 ). For the propagation of BAWs, the acoustic impedance of the substrate and the quality factor of the resonator are crucial factors to consider (Kvashnin et al 2022 ; Xie et al 2023 ). Significant attenuation of BAWs can result from both the inhomogeneity of the acoustic impedance of the piezoelectric substrate and the low-quality factor of the resonator (Xie et al 2023 ; Alekseev et al 2023 ).…”