Selected Area Manipulation of MoS2 via Focused Electron Beam-Induced Etching for Nanoscale Device Editing

John Lasseter, Spencer Gellerup, Sujoy Ghosh, Seok Joon Yun, Rama Vasudevan, Raymond R. Unocic, Olugbenga Olunloyo, Scott T. Retterer, Kai Xiao, Steven J. Randolph, Philip D. Rack

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We demonstrate direct-write patterning of single and multilayer MoS2 via a focused electron beam-induced etching (FEBIE) process mediated with the XeF2 precursor. MoS2 etching is performed at various currents, areal doses, on different substrates, and characterized using scanning electron and atomic force microscopies as well as Raman and photoluminescence spectroscopies. Scanning transmission electron microscopy reveals a sub-40 nm etching resolution and the progression of point defects and lateral etching of the consequent unsaturated bonds. The results confirm that the electron beam-induced etching process is minimally invasive to the underlying material in comparison to ion beam techniques, which damage the subsurface material. Single-layer MoS2 field-effect transistors are fabricated, and device characteristics are compared for channels that are edited via the selected area etching process. The source-drain current at constant gate and source-drain voltage scale linearly with the edited channel width. Moreover, the mobility of the narrowest channel width decreases, suggesting that backscattered and secondary electrons collaterally affect the periphery of the removed area. Focused electron beam doses on single-layer transistors below the etching threshold were also explored as a means to modify/thin the channel layer. The FEBIE exposures showed demonstrative effects via the transistor transfer characteristics, photoluminescence spectroscopy, and Raman spectroscopy. While strategies to minimize backscattered and secondary electron interactions outside of the scanned regions require further investigation, here, we show that FEBIE is a viable approach for selective nanoscale editing of MoS2 devices.

Original languageEnglish
Pages (from-to)9144-9154
Number of pages11
JournalACS Applied Materials and Interfaces
Volume16
Issue number7
DOIs
StatePublished - Feb 21 2024

Funding

All research was performed at the Center for Nanophase Materials Sciences, which is a U.S. Department of Energy Office of Science user facility at Oak Ridge National Laboratory (ORNL). Support for S.J.R. was partially provided through Laboratory Directed Research and Development Program funds of Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, for the U.S. Department of Energy. The synthesis of 2D materials (S. J. Y.) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Two UTK SMART program summer interns, B. Hedrick and D. Narcho, assisted in process development.

Keywords

  • direct write
  • electron beam-induced etching
  • nanofabrication
  • patterning
  • two-dimensional materials

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