title: Efficient Nitrogen Doping of Single-Layer Graphene Accompanied by Negligible Defect Generation for Integration into Hybrid Semiconductor Heterostructures.
abstract: While doping enables application-specific tailoring of graphene properties, it can also produce high defect densities that degrade the beneficial features. In this work, we report efficient nitrogen doping of ∼11 atom % without virtually inducing new structural defects in the initial, large-area, low defect, and transferred single-layer graphene. To shed light on this remarkable high-doping-low-disorder relationship, a unique experimental strategy consisting of analyzing the changes in doping, strain, and defect density after each important step during the doping procedure was employed. Complementary micro-Raman mapping, X-ray photoelectron spectroscopy, and optical microscopy revealed that effective cleaning of the graphene surface assists efficient nitrogen incorporation accompanied by mild compressive strain resulting in negligible defect formation in the doped graphene lattice. These original results are achieved by separating the growth of graphene from its doping. Moreover, the high doping level occurred simultaneously with the epitaxial growth of n-GaN micro- and nanorods on top of graphene, leading to the flow of higher currents through the graphene/n-GaN rod interface. Our approach can be extended toward integrating graphene into other technologically relevant hybrid semiconductor heterostructures and obtaining an ohmic contact at their interfaces by adjusting the doping level in graphene.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Hahn-Meitner Platz 1, 14109 Berlin, Germany.|Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.
authors.forename: George
authors.initials: G
authors.lastname: Sarau
authors.affiliation: Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Heilmann
authors.affiliation: Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.|Jacob Blaustein Institutes for Desert Research, Sede Boqer Campus, Ben-Gurion University of the Negev , 8499000 Sede Boqer, Israel.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Bashouti
authors.affiliation: Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.|Institute of Optics, Information and Photonics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstrasse 7/B2, 91058 Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Latzel
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Hahn-Meitner Platz 1, 14109 Berlin, Germany.|Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Tessarek
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Hahn-Meitner Platz 1, 14109 Berlin, Germany.|Max Planck Institute for the Science of Light , Staudtstrasse 2, 91058 Erlangen, Germany.|Physics Department, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Silke
authors.identifier: http://orcid.org/0000-0002-4908-4087
authors.initials: S
authors.lastname: Christiansen
keywords: doping; gallium nitride; graphene; hybrid; metal−organic vapor-phase epitaxy