title: Chemical Vapor Deposition Synthesized Atomically Thin Molybdenum Disulfide with Optoelectronic-Grade Crystalline Quality.
abstract: The ability to synthesize high-quality samples over large areas and at low cost is one of the biggest challenges during the developmental stage of any novel material. While chemical vapor deposition (CVD) methods provide a promising low-cost route for CMOS compatible, large-scale growth of materials, it often falls short of the high-quality demands in nanoelectronics and optoelectronics. We present large-scale CVD synthesis of single- and few-layered MoS2 using direct vapor-phase sulfurization of MoO2, which enables us to obtain extremely high-quality single-crystal monolayer MoS2 samples with field-effect mobility exceeding 30 cm(2)/(V s) in monolayers. These samples can be readily synthesized on a variety of substrates, and demonstrate a high-degree of optoelectronic uniformity in Raman and photoluminescence mapping over entire crystals with areas exceeding hundreds of square micrometers. Because of their high crystalline quality, Raman spectroscopy on these samples reveal a range of multiphonon processes through peaks with equal or better clarity compared to past reports on mechanically exfoliated samples. This enables us to investigate the layer thickness and substrate dependence of the extremely weak phonon processes at 285 and 487 cm(-1) in 2D-MoS2. The ultrahigh, optoelectronic-grade crystalline quality of these samples could be further established through photocurrent spectroscopy, which clearly reveal excitonic states at room temperature, a feat that has been previously demonstrated only on samples which were fabricated by micro-mechanical exfoliation and then artificially suspended across trenches. Our method reflects a big step in the development of atomically thin, 2D-MoS2 for scalable, high-quality optoelectronics.
authors.affiliation: Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.|Materials Synthesis and Integrated Devices, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Ismail
authors.initials: I
authors.lastname: Bilgin
authors.affiliation: Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.
authors.forename: Fangze
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.
authors.forename: Anthony
authors.initials: A
authors.lastname: Vargas
authors.affiliation: Department of Physics, Southern Illinois University Carbondale , Carbondale, Illinois 62901, United States.|Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa 904-0495, Japan.
authors.forename: Andrew
authors.initials: A
authors.lastname: Winchester
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa 904-0495, Japan.
authors.forename: Michael K L
authors.initials: MK
authors.lastname: Man
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University , Boston, Massachusetts 02115, United States.
authors.forename: Moneesh
authors.initials: M
authors.lastname: Upmanyu
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa 904-0495, Japan.
authors.forename: Keshav M
authors.initials: KM
authors.lastname: Dani
authors.affiliation: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Gautam
authors.initials: G
authors.lastname: Gupta
authors.affiliation: Department of Physics, Southern Illinois University Carbondale , Carbondale, Illinois 62901, United States.|Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa 904-0495, Japan.
authors.forename: Saikat
authors.initials: S
authors.lastname: Talapatra
authors.affiliation: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Aditya D
authors.initials: AD
authors.lastname: Mohite
authors.affiliation: Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.|George J. Kostas Research Institute for Homeland Security, Northeastern University , Burlington, Massachusetts 01803, United States.
authors.forename: Swastik
authors.initials: S
authors.lastname: Kar
keywords: Raman; chemical vapor deposition; exciton dissociation; monolayer MoS2; photocurrent spectroscopy; photoluminescence