Who: Alexander Fedorov (Univ. Köln and IFW Dresden, Germany and St Petersburg State University, Russia)
Place: Donostia International Physics Center
Date: Wednesday, 2 November 2016, 12:00
Electronic properties of doped graphene and graphene nanoribbons: Photoemission study
Universität zu Köln, Köln Germany, IFW Dresden, Dresden, Germany, St Petersburg State University, St Petersburg, Russia
Tailoring of the material electronic properties is the key issue for the developing new generation electronic devices. The unique properties of graphene and the numerous possibilities for its applications have made it one of the most promising for the future application. Due to graphene?s simple structure and the ease by which it can be functionalized chemically to tune its electronic properties it is a unique platform for both general study and applications. From one hand atoms and functional chemical groups may be adsorbed on its surface. From other hand, incorporation of guest atoms, like boron or nitrogen, into the graphene lattice allows one to modify the type of conductivity, and to tune the concentration of charge carriers. Such modifications of electronic structure and physicochemical properties greatly extend capabilities of the doped graphene use in fuel cells, batteries, supercapacitors, in oxygen reduction reactions, etc.
Electronically doped graphene is interested from the general point of view since the phonon-mediated superconductivity just recently has been observed in the 2D materials, however it is well established in many carbon related materials. For instance, in 3D analog of graphene ? alkali doped graphite. Therefore heavy electron-doped graphene is a good candidate for observation of 2D conventional superconductivity. By applying in combination photoemission and photo absorption spectroscopies, we examined both chemical properties and electron-phonon coupling in doped graphene.
Despite many unique properties and wide range of possible functionalization conduction properties of the graphene are limiting its application on the field effect transistors (FET). However the gapless electronic structure can be easily modified by applying the quantum confinement. Recent progress in the interface stimulated self-assembling chemical reactions opened an avenue for production of wide range of graphene nanoribbons (GNRs). Their electronic properties are governed both by their structural properties (width) and by the chemical impurities introduced in the graphene lattice or adsorbed on its surface. Here we show semiconductor ? metal transition in the alkali doped 7 atom width GNRs using angular resolved photoemission.