Electronic transport experiments through free-standing graphene nanoribbons performed with atomic-scale control

Abstract

Abstract Graphene nanoribbons (GNRs) are a promising element in the toolbox for beyond-silicon computing architectures since electronic properties like the band gap or spin polarisation are sensitive even to single-atomic changes of the ribbon’s atomic structure. This sensitivity allows to chemically design GNRs with tailored electronic properties for integration in devices. To date, a large variety of different types of atomically precise GNRs have been prepared and characterised experimentally. This has been done by a combination of on-surface synthesis and scanning probe microscopy and spectroscopy, respectively. Despite a high research interest, experiments evaluating the transport properties of atomically precise GNRs are seldomly performed. Here, I discuss scanning tunnelling microscopy (STM)-based transport experiments through free-standing single graphene nanoribbons suspended between tip and substrate of the STM. I focus on experimental details and challenges related to the creation of the fragile transport junction. The technique provides atomic-scale control over the nanoribbon and the entire transport junction allowing a detailed characterisation of the ribbon’s electronic properties. Importantly, perturbations due to a hybridisation of the GNR’s electronic states with the underlying metal substrate are minimised by suspending the ribbon, giving access to the intrinsic transport response of the system. The characterisation of electronic transport through the ribbon is vital for evaluating its technological potential in gatable devices.