Inhomogeneous screening of gate electric field by interface states in graphene FETs. (17th August 2017)

• Record Type: Journal Article
• Authors: Singh, Anil Kumar; Gupta, Anjan Kumar
• Is Part Of: Journal of physics. Volume 29:Number 38(2017)
• Publication Date: 2017-08-17
• Subjects: graphene -- interface States -- scanning tunneling spectroscopy; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa7dbf
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: The electronic states at graphene-SiO2 interface and their inhomogeneity is investigated using the back-gate-voltage dependence of local tunnel spectra acquired with a scanning tunneling microscope. The conductance spectra show two, or occasionally three, minima that evolve along the bias-voltage axis with the back gate voltage. This evolution is modeled using tip-gating and interface states. The energy dependent interface states' density, D i t ( E ), required to model the back-gate evolution of the minima, is found to have significant inhomogeneity in its energy-width. A broad D i t ( E ) leads to an effect similar to a reduction in the Fermi velocity while the narrow D i t ( E ) leads to the pinning of the Fermi energy close to the Dirac point, as observed in some places, due to enhanced screening of the gate electric field by the narrow D i t ( E ) . Finally, this also demonstrates STM as a tool to probe the density of interface states in various 2D Dirac materials.