Electronic structure characterization of atomically-precise chiral graphene nanoribbons on gold surfaces

Abstract

Resumen del póster presentado a la 13th European Conference on Surface Crystallography and Dynamics, celebrada en Donostia-San Sebastián (España) del 19 al 21 de junio de 2017.Graphene nanoribbons (GNRs) are narrow stripes of graphene that have attracted great attention because of their interest for both fundamental physics and promising applications. While sharing many of the appealing properties of their predecessor material graphene, such as high mobility charge-carriers and high specific surface area, they overcome some of its limitations as is the lack of a band gap. These nanostructures can display different edge orientations with respect to graphene´s lattice vectors that largely determine their main properties. Therefore three types of ribbons can be synthesized: armchair, zigzag or chiral GNRs, the latter ones presenting a periodic combination of both armchair- and zigzag-like segments. A recently established bottom-up synthesis method based on the use of molecular precursors as building blocks allows for the synthesis of these three types of GNRs with atomic precision. However, the limited experimental results on these structures are mostly focused on the electronic structure of armchair and, to a lesser extent, on zigzag GNRs, thus letting chiral GNRs (cGNRs) hardly explored. The growth of these ribbons on different noble metals was recently reported, hence we focus on the electronic structure of these nanomaterials. Here, using the same molecular precursor-based methodology, we report on the electronic structure of (3,1)-cGNRs on Au(111) by Scanning Tunneling Spectroscopy (STS). Moreover, the use of Au(322) vicinal substrate as template promotes the aligned growth of these ribbons along the terrace length thus enabling us to characterize the valence band by means of ARPES. Our results reveal a semiconducting bandgap on these chiral nanoribbons therefore confirming its potential applications for nanoelectronics.Peer reviewe