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Indirect Band Gap in Scrolled MoS2 Monolayers.
Jeonghyeon Na1, Changyeon Park1, Chang Hoi Lee1
1School of Physics, Konkuk University, Seoul 05029, Korea.
Nanomaterials (Basel, Switzerland)
|October 14, 2022
Summary
Researchers created molybdenum disulfide (MoS2) nanoscrolls from monolayers. These nanoscrolls exhibit tunable band gaps, shifting from direct to indirect, offering new possibilities for 2D material applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Molybdenum disulfide (MoS2) is a 2D material with tunable electronic properties.
- Modifying the structure of 2D materials, such as rolling them into scrolls, can alter their band gaps.
Purpose of the Study:
- To investigate the optical and transport band gaps of MoS2 nanoscrolls.
- To understand how the scrolling process affects the electronic properties of MoS2 monolayers.
- To explore MoS2 nanoscrolls as quasi-1D nanostructures.
Main Methods:
- Generation of MoS2 nanoscrolls from MoS2 monolayers with inner core radii of approximately 250 nm.
- Photoluminescence spectroscopy to determine optical band gaps.
- Transport measurements using ambipolar ionic-liquid-gated transistors to determine transport band gaps.
Main Results:
- MoS2 monolayers, initially direct gap semiconductors (~1.85 eV), transition to indirect gap semiconductors (~1.6 eV) upon scrolling.
- The indirect band gap of MoS2 nanoscrolls (~1.6 eV) is larger than that of MoS2 bilayers (~1.54 eV), suggesting weaker interlayer interactions.
- Transport measurements revealed a band gap of approximately 1.9 eV for the nanoscrolls.
- An exciton binding energy of 0.3 eV was determined for the MoS2 nanoscrolls.
Conclusions:
- Rolling 2D MoS2 atomic layers into nanoscrolls creates novel quasi-1D nanostructures.
- The scrolling process significantly modifies the band gap of MoS2, offering a new method for tuning electronic properties of 2D materials.
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