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PhD Defense: On-surface synthesis and electronic structure characterization of graphene nanoribbons

Tuesday, November 12, 2019 - 11:00
CFM Auditorium
Néstor Merino Díez, Nanoimaging Group, nanoGUNE
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This thesis presents a comprehensive study on the on-surface bottom-up synthesis, based on the use of aromatic molecular precursors, and the characterization of the electronic structure of different types of graphene nanoribbons (GNRs) formed on coinage metallic surfaces, being gold the most present substrate. Since GNRs derive from graphene, they preserve many of its interesting properties, such as the highest electron conductivity. In addition, the reduced dimensionality of GNRs provide them with a tunable non-zero electrical band gap, not present in graphene, and required for its implementation into electronic devices. Moreover, and again in contrast with graphene, the presence of edges in GNRs brings the emergence of magnetic edge states with promising applications in spintronics. Here, we demonstrate that GNRs feature a semiconducting behavior with a band gap tunable in terms of the nanoribbon width, a parameter which can also rule the emergence of edge-states in these nanostructures. Furhtermore we study how, the use of different molecular precursors and/or different metallic substrates, favours or limits the formation of a certain type of GNR. The experimental technique mainly employed is scanning tunneling microscopy/spectroscopy (STM/STS), together with supplementary surface sensitive techniques such as X-ray photoemission spectroscopy (XPS) and angle-resolved photoemission spectroscopy (ARPES), and theoretical simulations or calculations mainly performed by DFT methodologies.


Dimas G. de Oteyza (DIPC & Ikerbasque)
José Ignacio Pascual (nanoGUNE)