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Ultrafast carrier and phonon dynamics in few-layer 2H-MoTe2
Zhen Chi1, Hailong Chen2, Qing Zhao1
1Center for Quantum Technology Research, School of Physics, Beijing Institute of Technology, Beijing 100081, China.
The Journal of Chemical Physics
|September 23, 2019
Summary
Femtosecond spectroscopy reveals ultrafast carrier and phonon dynamics in few-layer 2H-MoTe2. Defect-assisted recombination and lattice thermalization occur within picoseconds after photoexcitation.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Ultrafast Spectroscopy
Background:
- Few-layer 2H-MoTe2 is a promising material for optoelectronic applications.
- Understanding carrier and phonon dynamics is crucial for device performance.
Purpose of the Study:
- Investigate ultrafast carrier and phonon dynamics in few-layer 2H-MoTe2 after photoexcitation.
- Elucidate the mechanisms of carrier relaxation and recombination.
- Determine the role of lattice thermalization in exciton energy shifts.
Main Methods:
- Femtosecond pump-probe spectroscopy with broadband near-infrared to mid-infrared detection.
- Time-resolved analysis of carrier and phonon interactions.
Main Results:
- Observed ultrafast hot carrier relaxation via phonon emission within hundreds of femtoseconds.
- Identified defect-assisted electron-hole recombination with a ~1.5 ps time constant.
- Confirmed lattice thermalization within 2 ps, causing exciton resonance redshift.
- Monitored phonon system cooling on a 100 ps timescale.
Conclusions:
- Ultrafast photoexcitation triggers rapid carrier relaxation and lattice heating in 2H-MoTe2.
- Defect-assisted recombination is a key process for carrier decay.
- Lattice thermalization significantly influences the material's optical properties.
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