P-Type Ohmic Contact to Monolayer WSe2Field-Effect Transistors Using High-Electron Affinity Amorphous MoO3

Yi Hsun Chen, Kaijian Xing, Song Liu, Luke N. Holtzman, Daniel L. Creedon, Jeffrey C. McCallum, Kenji Watanabe, Takashi Taniguchi, Katayun Barmak, James Hone, Alexander R. Hamilton, Shao Yu Chen, Michael S. Fuhrer

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3 Citations (Scopus)


Monolayer tungsten diselenide (1L-WSe2) has been widely used for studying emergent physics due to the unique properties of its valence bands. However, electrical transport studies have been impeded by the lack of a reliable method to realize Ohmic hole-conducting contacts to 1L-WSe2 especially at low carrier densities and low temperatures. Here, we report low-temperature p-type Ohmic contact to 1L-WSe2 field-effect transistors at carrier densities (n) below n = 1 × 1012 cm-2 with negligible temperature dependence down to the lowest measured temperature (10 K). The non-rectifying barrier is achieved between 1L-WSe2 and molybdenum trioxide (MoO3), where 1L-WSe2 underneath MoO3 is heavily hole-doped through surface transfer doping. Electrical transport measurements reveal linear current-voltage relations at a temperature of 10 K and carrier densities from n = 7.7 × 1011 cm-2 to below the threshold. The finding is also supported by nearly temperature-independent output curves up to room temperature and a negligible contact barrier down to the subthreshold regime. Furthermore, the contact resistivity of MoO3-contacted 1L-WSe2 FET is 30.2-64.8 kω μm at n = 1.5 × 1012 cm-2, which is the lowest reported for 1L-WSe2 FETs at such low carrier density. Realizing robust p-type Ohmic contact to a 2D transition metal dichalcogenide semiconductor will enable direct electronic measurements of quantum transport in correlated phases in the valence bands of monolayer semiconductors.

Original languageEnglish
Pages (from-to)5379–5386
Number of pages8
JournalACS Applied Electronic Materials
Issue number11
Publication statusPublished - 22 Nov 2022


  • contact resistance
  • molybdenum trioxide (MoO)
  • monolayer WSe
  • Ohmic contact
  • p-type semiconductor
  • surface charge transferring

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