Ultrafast Terahertz Complex Conductivity Dynamics of Layered MoS2 Crystal Probed by Time-Resolved Terahertz Spectroscopy

Frontiers in Physics

Lipeng Zhu¹  Yixuan Zhou²  Chuan He²  Yuanyuan Huang²  Xinlong Xu²  Yong Yang² 

[1] School of Electronic Engineering, Xi’an University of Posts and Telecommunications, Xi’an, China;Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, School of Physics, Institute of Photonics and Photon-Technology, Northwest University, Xi’an, China;

关键词: layered MoS2 crystal;    time-resolved terahertz spectroscopy;    ultrafast carrier dynamics;    exciton dynamics;    terahertz photoconductivity;   

DOI  :  10.3389/fphy.2021.764122

来源: DOAJ

【 摘 要 】

Ultrafast carrier dynamics, including the carrier photoexcitation and relaxation processes, plays an essential role in improving the performance of molybdenum disulfide (MoS2)-based optoelectronic devices. Herein, we investigate the photo-generated carrier dynamics in layered MoS2 crystal using a time-resolved terahertz (THz) spectroscopy. We have analyzed the ultrafast changes of the THz complex photoconductivity deduced from the peak and zero-crossing of THz waveforms. The decay time of the real part of the THz photoconductivity in layered MoS2 crystal is independent with the pump power, while the imaginary part increases with the pump power. We attribute the decay time of the real part to the carrier recombination process via phonon-assistance and the decay time of the imaginary part to the defect-assisted exciton recombination. The peak values of the complex photoconductivity show a trend of saturation with the increase of the pump power because of the many-body effect at high carrier concentration. This work deepens the understanding of the basic ultrafast physical process in MoS2 crystal, which is enlightening for the design of novel optoelectronic devices.

【 授权许可】

Unknown