Solidly Mounted Two-Dimensional Guided Modes in 30% Scandium Aluminum Nitride on Sapphire

This work reports the first demonstration and dispersion analysis of guided S0 Lamb modes in 30% scandium aluminum nitride (ScAlN) on sapphire (SoS). The fundamental Rayleigh and solidly mounted S0 Lamb mode are evaluated and compared in terms of electromechanical coupling as a function of film thickness with respect to wavelength. The propagation loss of each mode is also experimentally characterized. This work explores how slow piezoelectric thin films on fast substrates allow the propagation of higher order modes that can enable higher coupling and operation frequency through lateral field excitation (LFE) resonators and delay lines.