Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors

Accepted version prior to typesetting for the following paper:

Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors, 2021 Nanotechnology 32 025203, https://doi.org/10.1088/1361-6528/abbb4a

Abstract: Metal contacts to two-dimensional layered semiconductors are crucial to the performance of field-effect transistors (FETs) and other applications of layered materials in nanoelectronics and beyond. In this work, the wetting behavior of very thin Au films on exfoliated MoS2 flakes was studied and evaluated as a nanoscale, self-assembled dry etch mask. Etching nanoscale pits into MoS2 flakes prior to metallization from the top of the flake forms edge sites that contribute some fraction of edge contacts in addition to top contacts for additional carrier injection and lower contact resistance. The morphology and thickness of Au islands and MoS2 were studied with scanning electron microscopy and atomic force microscopy before and after etching with low-power plasmas. A Cl2 plasma etch of 10 s with a Au island mask of 6 nm (nominal) showed the best resulting morphology among the plasma conditions studied. Back-gated MoS2-based FETs on SiO2/p+-Si with Ti/Au contacts were fabricated using a Cl2 etch of only the contact regions, and they yielded devices with ON currents of 100s µA/µm, ON/OFF ratios ⩾106, and contact resistance <10 kΩ µm. The best set of devices had a very low contact resistance of ∼1 kΩ µm with almost no dependence of contact resistance on gating. Using nanoscale etch masks made from metal islands could be highly customizable and shows promise for engineering FETs with low contact resistance.

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Work Title Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors
Access
Open Access
Creators
  1. Timothy N. Walter
  2. Nailah Oliver
  3. Suzanne E. Mohney
Keyword
  1. MoS2
  2. Molybdenum disulfide
  3. 2D semiconductor
  4. Transition metal dichalcogenide
  5. Ohmic contact
  6. Field effect transistor
  7. Au islands
  8. Edge contacts
  9. Cl2 dry etch
  10. Dewetting
License In Copyright (Rights Reserved)
Work Type Article
Acknowledgments
  1. The authors acknowledge funding from the National Science Foundation through Grant No. 1433378. Any opinions, find- ings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors declare no conflicts of interest.
Publisher
  1. Nanotechnology
Publication Date October 14, 2020
Subject
  1. Electronics, electronic materials, semiconductors, devices
Language
  1. English
Publisher Identifier (DOI)
  1. https://doi.org/10.1088/1361-6528/abbb4a
Deposited December 21, 2021

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Version 1
published

  • Created

    December 21, 2021 13:23 by sem2

  • Updated Acknowledgments Show Changes

    December 21, 2021 13:24 by sem2

    Acknowledgments
    • The authors acknowledge funding from the National Science Foundation through Grant No. 1433378. Any opinions, find- ings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors declare no conflicts of interest.
  • Added Creator Timothy N. Walter

    December 21, 2021 13:24 by sem2

  • Added Creator Nailah Oliver

    December 21, 2021 13:24 by sem2

  • Added Creator Suzanne Mohney

    December 21, 2021 13:24 by sem2

  • Added Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors_Nanotechnology.pdf

    December 21, 2021 13:25 by sem2

  • Updated Subject, Language, License Show Changes

    December 21, 2021 13:26 by sem2

    Subject
    • Electronics, electronic materials, semiconductors, devices
    Language
    • English
    License
    • https://rightsstatements.org/page/InC/1.0/
  • Published

    December 21, 2021 13:26 by sem2

  • Updated

    March 22, 2022 16:18 by [unknown user]

  • Updated Keyword, Publisher, Publisher Identifier (DOI), and 3 more Show Changes

    February 29, 2024 14:15 by avs5190

    Keyword
    • MoS2, molybdenum disulfide, 2D semiconductor, transition metal dichalcogenide, ohmic contact, field effect transistor, Au islands
    • MoS2, Molybdenum disulfide, 2D semiconductor, Transition metal dichalcogenide, Ohmic contact, Field effect transistor, Au islands, Edge contacts, Cl2 dry etch, Dewetting
    Publisher
    • IOPScience
    • Nanotechnology
    Publisher Identifier (DOI)
    • 10.1088/1361-6528/abbb4a
    • https://doi.org/10.1088/1361-6528/abbb4a
    Description
    • Accepted version prior to typesetting for the following paper:
    • Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors, 2021 Nanotechnology 32 025203, https://doi.org/10.1088/1361-6528/abbb4a
    • Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors, 2021 Nanotechnology 32 025203, https://doi.org/10.1088/1361-6528/abbb4a
    • Abstract: Metal contacts to two-dimensional layered semiconductors are crucial to the performance of field-effect transistors (FETs) and other applications of layered materials in nanoelectronics and beyond. In this work, the wetting behavior of very thin Au films on exfoliated MoS2 flakes was studied and evaluated as a nanoscale, self-assembled dry etch mask. Etching nanoscale pits into MoS2 flakes prior to metallization from the top of the flake forms edge sites that contribute some fraction of edge contacts in addition to top contacts for additional carrier injection and lower contact resistance. The morphology and thickness of Au islands and MoS2 were studied with scanning electron microscopy and atomic force microscopy before and after etching with low-power plasmas. A Cl2 plasma etch of 10 s with a Au island mask of 6 nm (nominal) showed the best resulting morphology among the plasma conditions studied. Back-gated MoS2-based FETs on SiO2/p+-Si with Ti/Au contacts were fabricated using a Cl2 etch of only the contact regions, and they yielded devices with ON currents of 100s µA/µm, ON/OFF ratios ⩾106, and contact resistance <10 kΩ µm. The best set of devices had a very low contact resistance of ∼1 kΩ µm with almost no dependence of contact resistance on gating. Using nanoscale etch masks made from metal islands could be highly customizable and shows promise for engineering FETs with low contact resistance.
    Publication Date
    • 2020
    • 2020-10-14
    Publisher's Statement
    • Accepted version prior to typesetting for the following paper:
    • Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors, 2021 Nanotechnology 32 025203, https://doi.org/10.1088/1361-6528/abbb4a
  • Renamed Creator Suzanne E. Mohney Show Changes

    February 29, 2024 14:15 by avs5190

    • Suzanne Mohney
    • Suzanne E. Mohney
  • Updated

    April 04, 2024 10:21 by [unknown user]