Modulation of Surface Acoustic Waves in Graphene via Two Cross Interdigitated Transducers
Man-Ting Shen1*, Chiu-Chun Tang1, D. C. Ling2, C. C. Chi1, Jeng-Chung Chen1
1Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan
2Department of Physics, Tamkang University, Tamsui Dist, Taiwan
* presenting author:MAN-TING SHEN,
We investigate surface acoustic wave (SAW) propagating in a graphene with tuned Fermi-level EF and the modulation of acoustoelectric current by two SAWs generated by a cross interdigitated transducers (IDT). Our device consists of CVD-grown graphene coated with an ion-gel gate on top, and transferred on LiNbO3 substrate. Two IDTs are employed outside graphene area and are placed at right angles to each other. Interference patterns of SAW are formed at the graphene area by applying a high frequency ac voltage to the IDTs, and EF of graphene is controlled by biasing dc voltages on the ion-gel gate. We find the phase shift and SAW attenuations evolved with EF by measuring acoustoelectric current in graphene. Moreover, as two SAW are launched simultaneously we are able to modulate the acoustoelectric current, suggesting the formation of a two-dimensional ‘‘egg-carton’’ density fluctuation in graphene. Our results have a strong implications in the development of novel acoustoelectronic devices, and pave a way to study modulated 2D massless Dirac electrons.

Keywords: surface acoustic wave, graphene, acoustoelectric current