A Two-Step Approach Towards the Growth of WS2 Monolayers from Solid Oxide Precursors

Activity: Talks and presentations › Conference presentations

Description

Atomically thin 2D WS2 shows extraordinary properties at the monolayer limit, such as direct bandgap of ~2eV, strong light absorption, high PL yield, excellent thermal stability, and mechanical flexibility. Strong light absorption at visible wavelengths opens great opportunities for its integration in optoelectronic devices.
For practical application of WS2, it is required to grow uniform and highly oriented WS2 monolayers with a control over the layer number. In this work [1], we present our results on two-step synthesis of WS2 mono- and multilayers by high-temperature sulfurization of oxygen-deficient tungsten oxide films obtained by pulsed laser deposition (PLD) on sapphire. PLD is an established method to grow high-quality oxides with sharp interfaces and offers great opportunities to control oxide crystallinity and composition.
We explore how the presence of intrinsic oxygen vacancies (Vo) in the tungsten suboxide (WOx) precursor leads to a more facile conversion from WOx to WS2 films in a CVD process. Our study suggests that Vo in the PLD-grown oxide may serve as niches for S atoms and facilitate the growth of WS2 crystals with high PL emission and large domain size. Based on atomic resolution STEM images we will discuss how single and bilayer WS2 crystal orientation develops for low-temperature compared to high-temperature grown precursors. Raman and PL spectroscopy, AFM, STEM, and XPS were used to analyze WOx composition and crystallinity and WS2 films’ properties.
[1] Miakota D.I., Canuelscu S., Submitted to ACS Nano
Period9 Feb 2022 → 11 Feb 2022
Degree of RecognitionInternational

Keywords

  • 2D materials
  • TMD
  • WS2
  • Crystal growth
  • CVD
  • PLD
  • Deposition
  • Oxides
  • XPS
  • AFM

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