title: Approach to multifunctional device platform with epitaxial graphene on transition metal oxide.
abstract: Heterostructures consisting of two-dimensional materials have shown new physical phenomena, novel electronic and optical properties, and new device concepts not observed in bulk material systems or purely three dimensional heterostructures. These new effects originated mostly from the van der Waals interaction between the different layers. Here we report that a new optical and electronic device platform can be provided by heterostructures of 2D graphene with a metal oxide (TiO2). Our novel direct synthesis of graphene/TiO2 heterostructure is achieved by C60 deposition on transition Ti metal surface using a molecular beam epitaxy approach and O2 intercalation method, which is compatible with wafer scale growth of heterostructures. As-grown heterostructures exhibit inherent photosensitivity in the visible light spectrum with high photo responsivity. The photo sensitivity is 25 times higher than that of reported graphene photo detectors. The improved responsivity is attributed to optical transitions between O 2p orbitals in the valence band of TiO2 and C 2p orbitals in the conduction band of graphene enabled by Coulomb interactions at the interface. In addition, this heterostructure provides a platform for realization of bottom gated graphene field effect devices with graphene and TiO2 playing the roles of channel and gate dielectric layers, respectively.
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: Jeongho
authors.initials: J
authors.lastname: Park
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.|University of Dayton Research Institute, Dayton, Ohio 45469-0170, USA.|Center of Excellence for Thin Film Research and Surface Engineering, University of Dayton, Dayton, Ohio 45469-0170, USA.
authors.forename: Tyson
authors.initials: T
authors.lastname: Back
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: William C
authors.initials: WC
authors.lastname: Mitchel
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: Steve S
authors.initials: SS
authors.lastname: Kim
authors.affiliation: Departments of Physics, University of Dayton, Dayton, Ohio 45469.
authors.forename: Said
authors.initials: S
authors.lastname: Elhamri
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: John
authors.initials: J
authors.lastname: Boeckl
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: Steven B
authors.initials: SB
authors.lastname: Fairchild
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Naik
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, OH 45433-7707.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Voevodin