Confining electrons in graphene on hexagonal boron nitride

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The main goal of this project is to explore different devices schemes for improving the quality of graphene quantum dots well beyond current standards. An enhanced control over the properties, and possibly even over the shape, of quantum dot devices will allow new sophisticate experiments to investigate excited state spectra in the few-carrier regime as well as charge and spin-relaxation times. All the proposed experiments focus on gaining increased device tunability as well as on reducing the influence of disorder potential. More specifically, we are planning two class of experiments, aimed either at directly improving the quality of today most advanced graphene quantum dot devices, or at addressing unsolved issues related to the influence of bulk and edge-roughness disorder. In the first case, we will combine our ultimate dot design with techniques for embedding graphene nanostructures between hexagonal boron nitride (hBN) thin layers, and employ local metallic top-gates to increase the systems tunability. This device concept will be applied in particular for new pulse-gate experiments to investigate relaxation times in graphene quantum dots, but it is expected to be a global strategy to improve the quality of graphene devices in general. The second class of planed experiments aims instead at addressing the more fundamental question of the role of flake-edges in bilayer graphene devices on hBN. In order to do so, we propose a novel "Corbino-like" device scheme, where the edges of the flake can be fully excluded from the current path. With both class of experiments, we expect make a significant contribution to the understanding of the transport properties of single- and bi-layer graphene nanostructures and quantum dot devices.