title: Vertical 2D/3D Semiconductor Heterostructures Based on Epitaxial Molybdenum Disulfide and Gallium Nitride.
abstract: When designing semiconductor heterostructures, it is expected that epitaxial alignment will facilitate low-defect interfaces and efficient vertical transport. Here, we report lattice-matched epitaxial growth of molybdenum disulfide (MoS2) directly on gallium nitride (GaN), resulting in high-quality, unstrained, single-layer MoS2 with strict registry to the GaN lattice. These results present a promising path toward the implementation of high-performance electronic devices based on 2D/3D vertical heterostructures, where each of the 3D and 2D semiconductors is both a template for subsequent epitaxial growth and an active component of the device. The MoS2 monolayer triangles average 1 μm along each side, with monolayer blankets (merged triangles) exhibiting properties similar to that of single-crystal MoS2 sheets. Photoluminescence, Raman, atomic force microscopy, and X-ray photoelectron spectroscopy analyses identified monolayer MoS2 with a prominent 20-fold enhancement of photoluminescence in the center regions of larger triangles. The MoS2/GaN structures are shown to electrically conduct in the out-of-plane direction, confirming the potential of directly synthesized 2D/3D semiconductor heterostructures for vertical current flow. Finally, we estimate a MoS2/GaN contact resistivity to be less than 4 Ω·cm(2) and current spreading in the MoS2 monolayer of approximately 1 μm in diameter.
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.|Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors: Dmitry
authors: D
authors: Ruzmetov
authors: Department of Materials Science and Engineering & Center for Two-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Kehao
authors: K
authors: Zhang
authors: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors: Gheorghe
authors: G
authors: Stan
authors: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors: Berc
authors: B
authors: Kalanyan
authors: Department of Materials Science and Engineering & Center for Two-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Ganesh R
authors: GR
authors: Bhimanapati
authors: Department of Materials Science and Engineering & Center for Two-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Sarah M
authors: SM
authors: Eichfeld
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: Robert A
authors: RA
authors: Burke
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: Pankaj B
authors: PB
authors: Shah
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: Terrance P
authors: TP
authors: O'Regan
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: Frank J
authors: FJ
authors: Crowne
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: A Glen
authors: AG
authors: Birdwell
authors: Department of Materials Science and Engineering & Center for Two-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Joshua A
authors: JA
authors: Robinson
authors: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors: Albert V
authors: AV
authors: Davydov
authors: Sensors and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States.
authors: Tony G
authors: TG
authors: Ivanov
keywords: 2D material heterostructures; GaN; MoS2; conductive atomic force microscopy; transition metal dichalcogenides; van der Waals epitaxy; vertical transport