Photoluminescence Enhancement in WS2Nanosheets Passivated with Oxygen Ions: Implications for Selective Area Doping

Yu Han Wang, Hsin Mei Ho, Xuan Long Ho, Li Syuan Lu, Shang Hsien Hsieh, Shuei De Huang, Hsiang Chih Chiu, Chia Hao Chen, Wen Hao Chang, Jonathon David White, Yu Hui Tang*, Wei Yen Woon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The dominant defect types in chemical-vapor-deposited (CVD) tungsten disulfide (WS2) monolayers (ML) were regulated through mask-assisted scattered-oxygen-ion (O+) implantation. A shadow mask allowed for two distinctive implantation regions: directly bombarded and mask-shaded. Upon direct implantation, photoluminescence (PL) was universally suppressed, whereas in the mask-shaded region, PL was enhanced by up to 500% at low doses before suppression at doses of >3 × 1013 ions/cm2. We verified that the introduction of scattered O+ ions and low-density structural atomic defects are the two prerequisites for PL enhancement by replacing O+ ions with C+ ions and eliminating the involvement of physisorbed gases or laser treatment. Density functional theory calculations were carried out, suggesting a possible mechanism for the vacancy-induced dangling bonds in WS2. Sulfur- or tungsten-related vacancies create in-gap deep trap states, hindering electron-hole recombination. Scattered-oxygen treatment passivates these sulfur vacancies by effectively eliminating these in-gap nonradiative pathways. In addition, it further increases the transition probability by creating more tungsten-dominated states near the conduction band edge through charge transfer. This work demonstrates a facile and successful single-step method to passivate sulfur vacancies with scattered oxygen ions. It has the potential to heal the PL quenching that originated from the intrinsic high defect density in a CVD-grown WS2 ML.

Original languageEnglish
Pages (from-to)11693-11699
Number of pages7
JournalACS Applied Nano Materials
Issue number11
Publication statusPublished - 2021 Nov 26


  • WSmonolayer
  • ion implantation
  • micropatterning
  • oxygen defects
  • photoluminescence enhancement

ASJC Scopus subject areas

  • General Materials Science


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