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Photoluminescence from chemically exfoliated MoS2
Goki Eda1, Hisato Yamaguchi, Damien Voiry
1Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK. g.eda@nus.edu.sg
Nano Letters
|November 1, 2011
Summary
Chemically exfoliated molybdenum disulfide (MoS2) can regain its semiconducting properties through annealing. Mild heat treatment restores the band gap photoluminescence in MoS2 monolayers, enabling their use in electronic applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Molybdenum disulfide (MoS2) monolayer is a direct gap semiconductor with photoluminescent properties, unlike its bulk form.
- Chemical exfoliation offers a scalable method for synthesizing MoS2 monolayers.
- Lithium (Li) intercalation during exfoliation can degrade MoS2's semiconducting properties.
Purpose of the Study:
- To investigate the structural and electronic properties of chemically exfoliated MoS2.
- To determine the effects of annealing on restoring semiconducting properties.
- To compare chemically exfoliated MoS2 with mechanically exfoliated counterparts.
Main Methods:
- Chemical exfoliation of bulk MoS2 via Li intercalation.
- Structural and electronic property characterization of as-exfoliated MoS2.
- Mild annealing of MoS2 at varying temperatures (up to 300 °C).
- Photoluminescence spectroscopy to assess band gap restoration.
Main Results:
- Chemically exfoliated MoS2 initially exhibits a metastable metallic phase due to Li intercalation.
- Mild annealing gradually restores the semiconducting phase of MoS2.
- Annealing above 300 °C results in prominent band gap photoluminescence, similar to mechanically exfoliated MoS2.
Conclusions:
- The metastable metallic phase in chemically exfoliated MoS2 can be reverted to the semiconducting phase through annealing.
- Annealing is an effective post-processing step to recover desirable electronic properties in chemically exfoliated MoS2.
- Chemically exfoliated MoS2, after annealing, shows potential for applications requiring semiconducting monolayers.
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