Ultraflat Sub-10 Nanometer Gap Electrodes for Two-Dimensional Optoelectronic Devices

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Two-dimensional (2D) materials are promising candidates for building ultrashort-channel devices because their thickness can be reduced down to a single atomic layer. Here, we demonstrate an ultraflat nanogap platform based on atomic layer deposition (ALD) and utilize the structure to fabricate 2D material-based optical and electronic devices. In our method, ultraflat metal surfaces, template-stripped from a Si wafer mold, are separated by an Al2O3 ALD layer down to a gap width of 10 nm. Surfaces of both electrodes are vertically aligned without a height difference, and each electrode is ultraflat with a measured root-mean-square roughness as low as 0.315 nm, smaller than the thickness of monolayer graphene. Simply by placing 2D material flakes on top of the platform, short-channel field-effect transistors based on black phosphorus and MoS2 are fabricated, exhibiting their typical transistor characteristics. Furthermore, we use the same platform to demonstrate photodetectors with a nanoscale photosensitive channel, exhibiting higher photosensitivity compared to microscale gap channels. Our wafer-scale atomic layer lithography method can benefit a diverse range of 2D optical and electronic applications.

Original languageEnglish (US)
Pages (from-to)5276-5283
Number of pages8
JournalACS nano
Issue number3
StatePublished - Mar 23 2021

Bibliographical note

Publisher Copyright:


  • atomic layer deposition
  • atomic layer lithography
  • field-effect transistor
  • photodetector
  • template stripping
  • two-dimensional materials

PubMed: MeSH publication types

  • Journal Article


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