title: Enhanced optical second-harmonic generation from the current-biased graphene/SiO2/Si(001) structure.
abstract: We find that optical second-harmonic generation (SHG) in reflection from a chemical-vapor-deposition graphene monolayer transferred onto a SiO2/Si(001) substrate is enhanced about 3 times by the flow of direct current electric current in graphene. Measurements of rotational-anisotropy SHG revealed that the current-induced SHG from the current-biased graphene/SiO2/Si(001) structure undergoes a phase inversion as the measurement location on graphene is shifted laterally along the current flow direction. The enhancement is due to current-associated charge trapping at the graphene/SiO2 interface, which introduces a vertical electric field across the SiO2/Si interface that produces electric field-induced SHG. The phase inversion is due to the positive-to-negative polarity switch in the current direction of the trapped charges at the current-biased graphene/SiO2 interface.
authors.affiliation: College of Nanoscale Science and Engineering, University at Albany, Albany, New York 12203, USA. yan2@albany.edu
authors.forename: Yong Q
authors.initials: YQ
authors.lastname: An
authors.forename: Florence
authors.initials: F
authors.lastname: Nelson
authors.forename: Ji Ung
authors.initials: JU
authors.lastname: Lee
authors.forename: Alain C
authors.initials: AC
authors.lastname: Diebold