title: Transfer of monolayer TMD WS2and Raman study of substrate effects.
abstract: A facile transfer process for transition metal dichalcogenide WS2flakes is reported and the effect of the underlying substrate on the flake properties is investigated using Raman spectroscopy. The flakes are transferred from their growth substrate using polymethyl methacrylate (PMMA) and a wet etch to allow the user to transfer the flakes to a final substrate using a microscope and micromanipulator combined with semi-transparent Kapton tape. The substrates used range from insulators such as industry standard high-k dielectric HfO2and "green polymer" parylene-C, to conducting chemical vapor deposition (CVD) grown graphene. Raman spectroscopy is used first to confirm the material quality of the transferred flakes to the substrates and subsequently to analyze and separate the effects arising from material transfer from those arising from interactions with the substrate. We observe changes in the Raman spectra associated with the interactions between the substrates in the flakes. These interactions affect both in-plane and out-of-plane modes in different ways depending on their sources, for example strain or surface charge. These changes vary with final substrate, with the strongest effects being observed for WS2transferred onto graphene and HfO2, demonstrating the importance of understanding substrate interaction for fabrication of future devices.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Jerome T
authors.initials: JT
authors.lastname: Mlack
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Masih Das
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Gopinath
authors.initials: G
authors.lastname: Danda
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Yung-Chien
authors.initials: YC
authors.lastname: Chou
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Carl H
authors.initials: CH
authors.lastname: Naylor
authors.affiliation: Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Néstor Perea
authors.initials: NP
authors.lastname: López
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Tianyi
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Terrones
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: A T Charlie
authors.initials: AT
authors.lastname: Johnson
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Marija
authors.initials: M
authors.lastname: Drndić