| Summary: | Devices were developed to explore the perturbation of graphene using high-frequency signals. Two kinds of effects were studied: the interaction of graphene with surface acoustic waves (SAWs) and the propagation of picosecond pulses. The coupling of graphene with SAWs was first studied using flip-chip devices, which employed an evanescent field extending across the gap between the chips. A later design directly integrated layers of graphene grown by chemical vapour deposition (CVD) on piezoelectric 5ubstrates, containing interdigital transducers (IDTs) for SAW generation and detection. Graphene devices were characterised using Raman spectroscopy and atomic force microscopy; the electronic properties of CVD-graphene were investigated by performing magnetoresistance measurements. The measurements of the acoustically-generated current in the direct-coupling devices closely followed the SAW response of the IDTs, demonstrating the acousto-electric effect in graphene for the first time . . In a second class of devices, graphene was transferred to a quartz substrate, and, using on-chip waveguides, integrated with photoconductive switches capable of generating and detecting sub-picosecond pulses, which allow studying THz-frequency transmission in the system. Pulses containing frequency components of up to 2.5 THz were generated in these devices. The demonstration of the acousto-electric effect in graphene paves the way for SAW-based charge manipulation in graphene, such as singleelectron transport. The propagation of picosecond pulses in graphene could be used to further investigate the properties of graphene in the terahertz-frequency range.
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