No abstract

In this study, the finite element method is employed to calculate SAW characteristics in (100) AlN/diamond based structures with different electrical interfaces; i.e., IDT/ AlN/diamond, AlN/IDT/diamond, IDT/AlN/thin metal film/ diamond, and thin metal film/AlN/IDT/diamond. The effects of Cu and Al electrodes as well as the thickness of electrode on phase velocity, coupling coefficient, and reflectivity of SAWs are illustrated. Propagation characteristics of SAWs in (002) AlN/diamond-based structures are also presented for comparison. Simulation results show that to retain a large reflectivity for the design of RF filters and duplexers, the Cu IDT/(100) AlN/diamond structure possesses the highest phase velocity and largest coupling coefficient at the smallest AlN film thickness- to-wavelength ratio.

The surface acoustic waves (SAWs) propagating in interdigital transducer (IDT)/(100) aluminum nitride (AlN)/diamond possess the greater phase velocity and coupling coefficient than those in IDT/(002) AlN/diamond. In this study, the finite element method (FEM) is employed to calculate SAW characteristics in these two layered structures with different electric interfaces; i.e., IDT/AlN/diamond, AlN/IDT/diamond, IDT/AlN/thin metal film/diamond, and thin metal film /AlN/IDT/diamond. The effects of Cu and Al electrodes on SAW characteristics are illustrated. Simulation results show that the Cu IDT/(100) AlN/diamond structure can support a SAW with a coupling coefficient of 1.71%, a phase velocity of 9705 m/s, and a reflectivity of 0.15, which is applicable for the miniaturized wideband and super high band applications.

In this study, propagation characteristics of surface acoustic waves (SAWs) in a layered piezoelectric structure consisting of an AlN thin film sputtered on 128°Y-X LiNbO 3 are investigated. The phase velocity and coupling coefficient of the layered structure with interdigital transducers (IDTs) and/or metal thin films deposited at various interfaces will be calculated numerically. The effects of the polarity of 128°Y-X LiNbO 3 on SAW characteristics are illustrated. By substituting the constituting relations into the Christoffel equations along with enforcing the appropriate boundary conditions on the interfaces, SAW characteristics of layered piezoelectric structures are determined by employing a matrix approach. Phase velocity and coupling coefficient of SAWs are presented versus h/λ, where h is the thickness of the AlN film and λ is the wavelength. Simulation results are compared with experimental data, which are calculated from S-parameter measurements of transversal SAW filters. A well matched comparison is demonstrated. Results obtained can be applied for the design of SAW devices using AlN/128°Y-X LiNbO 3 structures.

Propagation characteristics of surface acoustic waves (SAWs) in IDT/(100) AlN/diamond structures are analyzed in this study using the finite element method (FEM). The extracted coupling-of-mode (COM) parameters are employed to calculate the frequency responses of two-track SAW filters using the transmission matrix method. To enhance the sideband suppression, Chebyshev function is adopted to modify the reflectivity distributions of reflectors, which can be realized using width-modulated reflectors. The copper electrode is used to retain a sufficiently high reflectivity. Simulation results show that a two-track SAW filter applicable for the CDMA system can be tailored using IDT/(100) AlN/diamond structures.