# Acoustoelectric transport at gigahertz frequencies in coated epitaxial graphene

## TL;DR

This paper demonstrates high-frequency surface acoustic wave (SAW) transport in coated epitaxial graphene on SiC, achieving over 7 GHz and significantly enhanced acoustoelectric currents, advancing dynamic control of charge carriers in graphene.

## Contribution

It introduces coated epitaxial graphene devices capable of GHz-frequency SAW propagation with improved acoustoelectric effects, enabling dynamic charge carrier manipulation.

## Key findings

- SAWs generated at frequencies over 7 GHz in coated EG.
- ZnO coating increases acoustoelectric currents by two orders of magnitude.
- Demonstrates potential for GHz-range acoustic control of graphene charge carriers.

## Abstract

Epitaxial graphene (EG) produced from SiC surfaces by silicon sublimation is emerging as a material for electronic applications due to its good electronic properties and availability over large areas on a semiconducting substrate. In this contribution, we report on the transport of charge carriers in EG on SiC using high-frequency ($>$ 1 GHz) surface acoustic waves (SAWs). In our devices, the EG is coated with hydrogen-silsesquioxane, SiO$_2$ and a ZnO layer. This allows the efficient generation of SAWs and is compatible with the deposition of a metal top gate. Measurements of frequency- and time-resolved power scattering parameters confirm the generation and propagation of SAWs with frequencies of up to more than 7 GHz. Furthermore, the ZnO coating enhances the acoustoelectric currents by two orders of magnitude as compared to our previous uncoated samples. These results are an important step towards the dynamic acoustic control of charge carriers in graphene at gigahertz frequencies.