Excitation of Surface Acoustic Waves and Lamb Waves at Superhigh Frequencies in a Diamond-Based Piezoelectric Layered Structure

The authors have carried out an experimental and theoretical study of the propagation of surface acoustic waves (SAW)—Rayleigh, Sezawa and SH-modes, as well as Lamb waves in Me-IDT/AlN/(100) diamond (Me = Pt, Al) piezoelectric layered structures with a SAW resonator configuration. The types of modes are identified and the dispersion curves of the phase velocities and electromechanical coupling coefficients for SAW and Lamb waves are obtained. The excitation of Lamb waves up to a frequency of 7.3 GHz was observed experimentally. The resonance curves for Lamb waves have a higher quality factor Q compared to surface acoustic waves propagating on the same substrates. At a frequency of about 7 GHz, the loaded Q-factor reaches 3400, while the quality parameter Q × f = 2.4 × 1013 Hz. An unusual effect of a significant increase in the Q-factor of Lamb waves with the frequency increasing from 760 at 1.5 GHz to 3400 at 7 GHz is noted.