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


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

ASJC Scopus subject areas

  • Materials Science(all)


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