Munis Khan, Quantum Device Physics Laboratory

Opponent: Helena Rodilla, Associate Professor, Terahertz and Millimetre Wave Laboratory

Examiner: Professor Dag Winkler

Abstract: A scalable method of producing large-area graphene is the chemical-vapor deposition (CVD) on copper foils. For practical applications, the graphene should be transferred to insulating carrier often through a cumbersome process, which results in significantly worsened graphene characteristics.
We present our technique of graphene transfer from the copper foil to ethylene vinyl acetate/polyethylene terephthalate (EVA/PET) foil by hot-press lamination as an easy- and affordable alternative to manufacture flexible, transparent, and conductive films. We demonstrate that annealing the samples at 60 °C under a flow of nitrogen drastically improves the transport properties of such graphene films, in which charge-carrier mobility reaches almost 10 000 cm2/(V s) at room temperature. We also present a probe-less terahertz time-domain spectroscopy on our samples offering a high-throughput contactless mapping, which directly reveals the presence of any inhomogeneities and defects. The transport properties extracted from such measurements are in a good agreement with the van-der-Pauw and Hall measurements. Finally, we report on a scalable fabrication method of a flexible graphene field-effect transistors (GFET’s) and their prospect for being used as highly sensitive and selective biosensors.