Operando Spectromicroscopy Observation of Many-Body Effects in Graphene Device

Abstract

Linear band dispersion causes peculiar behaviour of device interfaces in graphene transistors. The vanishment of density of states (DOS) near the Dirac point due to the linear band dispresion renormalizes quasiparticles behaviours of electrons, i.e. many-body effects, such as excitonic effects and the Anderson orthogonality catastrophe (AOC) which occur through the interactions of conduction electrons with holes. For this reason, we have studied the impact of the excitonic effects and the AOC on graphene device performance by using x-ray absorption spectromicroscopy on an actual graphene transistor in operation. Our work shows that the excitonic effect and the AOC are tunable by gate bias or metal contacts, both of which alter the Fermi energy. In addition, it is found that these many-body effects are orbital-specifi c, appreciable many-body effects on π * orbital, while negligible on σ * orbital.