Normally off WSe2Nanosheet-Based Field-Effect Transistors with Self-Aligned Contact Doping

Dongryul Lee, Jin Yong An, Chul Ho Lee, Ki Wan Bong, Jihyun Kim

Research output: Contribution to journalArticlepeer-review


Despite the advantages of ambipolar semiconductors, high off-currents and narrow off-state bias window limit their application in enhancement-mode field-effect transistors (FETs). We demonstrate the normally off operation of a low-dimensional ambipolar WSe2semiconductor FET by forming the lateral p-n homojunction. The self-aligned n-doping of the ambipolar WSe2was obtained by intentionally forming Se vacancy via mild Ar-ion treatment. The UV-ozone-assisted growth of the WOXlayer increased the hole concentrations of the WSe2channel, where its high work function makes the underlying WSe2electron-deficient. A high on/off ratio of ∼108and a wide off-range gate bias with the normally off operation were obtained in the n-p-n nanostructured WSe2FETs, which was also characterized by photocurrent mapping analysis. The electrical characteristics of the devices exhibited their thermal stability up to an operating temperature of 140 °C, which was enabled by the formation of the p-n homojunction barrier. High on/off ratios, wide off-range bias, and decent field-effect carrier mobility of the normally off nanosheet-based WSe2FET were well maintained at elevated temperatures, which indicates that the low-dimensional ambipolar semiconductor with a junction barrier can play a pivotal role in the next-generation device architecture.

Original languageEnglish
Pages (from-to)18462-18468
Number of pages7
JournalACS Applied Nano Materials
Issue number12
Publication statusPublished - 2022 Dec 23

Bibliographical note

Funding Information:
This research was financially supported by the Institute of Civil Military Technology Cooperation Center funded by the Defense Acquisition Program Administration and Ministry of Trade, Industry and Energy, and of the Korean government under grant No. 20-CM-BR-05, and the National Research Foundation (NRF) of Korea funded by the Ministry of Science and ICT (2022M3H4A1A01010280), and the K-Sensor Development Program (No. RS-2022-00154729), funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea).

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.


  • field-effect transistors
  • normally off devices
  • plasma treatment
  • self-aligned process
  • van der Waals materials

ASJC Scopus subject areas

  • General Materials Science


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