Acoustoelectric Current in Graphene Nanoribbons

T Poole,G R Nash

doi:10.1038/s41598-017-01979-8

Abstract

Surface acoustic waves (SAWs) propagating on piezoelectric substrates offer a convenient, contactless approach to probing the electronic properties of low-dimensional charge carrier systems such as graphene nanoribbons (GNRs). SAWs can also be used to transport and manipulate charge for applications such as metrology and quantum information. In this work, we investigate the acoustoelectric effect in GNRs, and show that an acoustoelectric current can be generated in GNRs with physical widths as small as 200 nm at room temperature. The positive current in the direction of the SAWs, which corresponds to the transportation of holes, exhibits a linear dependence on SAW intensity and frequency. This is consistent with the description of the interaction between the charge carriers in the GNRs and the piezoelectric fields associated with the SAWs being described by a relatively simple classical relaxation model. Somewhat counter-intuitively, as the GNR width is decreased, the measured acoustoelectric current increases. This is thought to be caused by an increase of the carrier mobility due to increased doping arising from damage to the GNR edges.

Highlights

Surface acoustic waves (SAWs) propagating on piezoelectric substrates offer a convenient, contactless approach to probing the electronic properties of low-dimensional charge carrier systems such as graphene nanoribbons (GNRs)
The ability of piezoelectric potentials to trap and transport charge at the speed of sound enables the generation of acoustoelectric currents. These have been measured in micron-scale graphene monolayers[7, 8], and we have previously studied the acoustoelectric response of large-area graphene sheets produced by chemical vapour deposition (CVD) transferred to LiNbO3 SAW devices at room temperature[9], low temperature[10], and under illumination[11]
The interdigital transducers (IDTs) were pre-defined on the surface by the manufacturer (MESL Microwave/COM DEV International) of the LiNbO3 crystal with an acoustic aperture of 3.25 mm and separation distance 5.4 mm, allowing large-area CVD graphene monolayers to be positioned between the transducers without shorting them out

Summary

Introduction

Surface acoustic waves (SAWs) propagating on piezoelectric substrates offer a convenient, contactless approach to probing the electronic properties of low-dimensional charge carrier systems such as graphene nanoribbons (GNRs). The ability of piezoelectric potentials to trap and transport charge at the speed of sound enables the generation of acoustoelectric currents These have been measured in micron-scale graphene monolayers[7, 8], and we have previously studied the acoustoelectric response of large-area graphene sheets produced by chemical vapour deposition (CVD) transferred to LiNbO3 SAW devices at room temperature[9], low temperature[10], and under illumination[11]. The electric potential associated with SAWs propagating on piezoelectric materials enables the confinement of charge carriers in nearby electronic systems, that could have applications in metrology and quantum computing[3, 4, 33,34,35]

Methods

Results

Conclusion