Acoustic Wave Engineering of Lamb Wave Resonators with 2D van der Waals Floating Electrode

Abstract

Lamb wave resonators with 2D van der Waals floating electrodes are investigated to overcome the intrinsic RF performance limitations of conventional floating electrodes. By utilizing graphene as the floating electrode and hexagonal boron nitride as an acoustic mirror, the resonators achieve enhanced resonance frequency, electromechanical properties, and energy confinement compared to the conventional Pt floating electrodes. Finite element method simulations show that the graphene floating electrode significantly enhances S0 mode resonance frequency and electromechanical coupling coefficient. Incorporating the hexagonal boron nitride interlayer further improves the Q-factor by 1.4 times, effectively confining acoustic energy within the AlN layer. The newly implemented 2D heterostructure demonstrates resonance frequencies above 7 GHz, a maximum figure of merit of 1152, and outstanding temperature stability with a temperature coefficient of frequency of −29.02 ppm/°C. This research demonstrates the potential for developing high-performance Lamb wave resonator operating in the cm-Wave band (7-15 GHz). Additionally, the 2D heterostructure provides a versatile platform adaptable to various acoustic wave devices.