UC Berkeley

While the discovery of 2D graphene offered incredible promise for next generation electronics, device fabrication was severely hindered by the semi metallic nature of graphene. Graphene nanoribbons (GNRs) are quasi-1D nanostructures with similar electronic properties to the parent graphene, and the additional benefit of a widely tunable band gap. The ability to modulate the band gap in GNRs makes them particularly promising candidates for high-performance electronic devices. The band gap in these materials is intimately linked to the atomic structure of the GNR and it is essential to understand the connection between electronic structure and various parameters such a width, dopant position/concentration, and edge topology. To determine this relationship, the synthesis of atomically precise GNRs is crucial. Traditional synthetic techniques for GNR synthesis (e.g. lithographic patterning or the unzipping of carbon nanotubes) fail to meet this requirement. Instead, this thesis will focus on bottom-up synthetic techniques where a molecular precursor is sublimed onto a metallic substrate to yield the desired GNR. Moreover, the metallic substrate provides the ideal platform for electronic and atomic structure characterization using Scanned Probe Microscopy (SPM) techniques.

In this thesis, I will begin by explaining exotic magnetic phenomena that emerge from graphene nanoribbons with zigzag edge topology (Chapter 2). This chapter will discuss all-carbon GNRs and GNRs with nitrogen dopants to ascertain the effect of the dopant atom. Next, I provide information about low band gap GNRs that could be ideal candidates for next generation electronic devices (Chapter 3). Afterwards, I will consider the potential to form Nitrogen bonds with the underlying metallic substrate (Chapter 4). The final chapters in this thesis will take advantage of topological engineering to access low band gap GNRs (Chapter 5) and metallic GNRs (Chapter 6) that can be used to construct high-performance electronic devices entirely from GNRs.