Observation of giant acoustoelectric currents in graphene on lead magnesium niobate–lead titanate

Abstract

Abstract Acoustoelectric (AE) devices enable coupling between acoustic waves and mobile charge carriers, offering a route toward RF-to-DC conversion, RF power sensing, energy harvesting, and responsive sensing applications. The efficiency of this coupling depends on both the electromechanical properties of the piezoelectric substrate and the transport properties of the conductive film interacting with the surface acoustic wave (SAW). Here an AE SAW delay line platform is presented for generating large AE currents using graphene on lead magnesium niobate–lead titanate (PMN–PT). Leveraging graphene’s high carrier mobility and the strong electromechanical coupling of (111)-cut PMN–PT, this platform achieves giant AE current generation. Additionally, AE responsivity ( $${{\boldsymbol{{\mathscr{R}}}}}_{{{\bf{AE}}}}$$ R AE ) is introduced here as a figure of merit for comparing AE platforms. The platform comprises interdigitated transducers (IDTs) deposited and patterned on the bulk PMN–PT surface for launching SAW and a monolayer graphene film positioned within the SAW propagation region. Experimental measurements confirm generation of AE current and voltage within the SAW passband, with the AE current reaching up to 90.39 µA at an RF input power of 20 dBm, corresponding to an $${{\boldsymbol{{\mathscr{R}}}}}_{{{\bf{AE}}}}$$ R AE of 7.66 µA/(W·MHz). The reported AE current and AE responsivity outperform most of the previously reported platforms, validating the effectiveness of the proposed approach.