Flip-chip gate-tunable acoustoelectric effect in graphene

TL;DR

This paper introduces a flip-chip device enabling low-temperature acoustoelectric measurements on graphene, revealing gate-tunable effects and charge-disorder influences through surface acoustic wave interactions.

Contribution

It presents a novel flip-chip device for acoustoelectric studies on 2D materials and demonstrates gate-tunable acoustoelectric effects in graphene.

Findings

Ambipolar dependence of acoustoelectric signal observed

Reduction in signal near charge neutrality due to charge disorder

Device enables dynamic control of charge carriers with high-frequency waves

Abstract

We demonstrate a flip-chip device for performing low-temperature acoustoelectric measurements on exfoliated two-dimensional materials. With this device, we study gate-tunable acoustoelectric transport in an exfoliated monolayer graphene device, measuring the voltage created as high-frequency surface acoustic waves dynamically drive the graphene charge carriers, the density of which we simultaneously control with a silicon back-gate. We demonstrate ambipolar dependence of the acoustoelectric signal, as expected from the sign of the graphene charge carriers. We observe a marked reduction in the magnitude of the acoustoelectric signal over a well-defined range of density in the vicinity of charge neutrality, which we attribute to a spatially heterogeneous charge-disorder landscape not directly revealed by conventional transport measurements.