Graphene Nanodevices

Abstract

This thesis describes a divergent set of experiments on graphene, a one-atom thin sheet of carbon. We employ graphene’s unique properties to explore fundamental physics and novel applications. This is done by nano fabricating graphene to nanodevices, which are subject to experiments. Here we first developed a water-based transfer method. The electronic quality of wet-transferred graphene does not significantly degrade, despite the presence of wrinkling in graphene. This transfer method allowed us to realise the first graphene nanopore device. With that device we were able detect single DNA molecules passing the nanopore. This is the first step towards a proto-type DNA sequencing device. Electronic transport from graphene in a superconductor is carried by Andreev reflection, notable by a doubling of the conductance. In disordered graphene/NbTiN junctions we have observed more than a doubling of the conductance, which can be understood by an enhancement of Andreev reflection mediated by disorder. We have used the tip of an atomic force micrscope to mechanically clean a graphene surface. The electronic quality improved after this cleaning treatments. This new method is particularly relevant when other methods are not effective or undesirable. For the first time we have observed ballistic transport in chemical vapour deposited (CVD) graphene on micron length scales. To realise this we have adapted a dry and clean transfer method to transfer CVD graphene onto hBN flakes. CVD graphene has the advantage that it is scalable and controllable, hence applicable for industrial purposes. While exfoliated graphene is widely used as a platform for fundamental research, CVD graphene may soon become an attractive alternative.