Scanning gate microscopy on graphene: charge inhomogeneity and extrinsic doping

Romaneh Jalilian, Purdue University
Luis A. Jauregui, Purdue University - Main Campus
Gabriel Lopez, Purdue University
Jifa Tian, Purdue University
Caleb Roecker, Purdue University
Mehdi Yazdanpanah, University of Louisville
Robert Cohn, University of Louisville
I. Jovanovic, Purdue University
Yong P. Chen, Purdue University

Date of this Version



ISSN: 0957-4484


We have performed scanning gate microscopy (SGM) on graphene field effect transistors (GFET) using a biased metallic nanowire coated with a dielectric layer as a contact mode tip and local top gate. Electrical transport through graphene at various back gate voltages is monitored as a function of tip voltage and tip position. Near the Dirac point, the response of graphene resistance to the tip voltage shows significant variation with tip position, and SGM imaging displays mesoscopic domains of electron-doped and hole-doped regions. Our measurements reveal substantial spatial fluctuation in the carrier density in graphene due to extrinsic local doping from sources such as metal contacts, graphene edges, structural defects and resist residues. Our scanning gate measurements also demonstrate graphene's excellent capability to sense the local electric field and charges.


Nanoscience and Nanotechnology