研究目的
Investigating the ultrafast electron cooling and decay dynamics in monolayer WS2 to understand their implications for optoelectronic applications.
研究成果
The study reveals that electron cooling in the Q valley of the conduction band occurs on a timescale of 0.3 ps, with electron decay mainly via defect trapping over several picoseconds. Laser illumination under ultra-high vacuum increases trap states, affecting carrier dynamics. This phenomenon is crucial for photoemission studies of two-dimensional materials.
研究不足
The study is limited by the resolution of the PEEM system and the potential introduction of defects during laser illumination, which could affect the intrinsic properties of the materials.
1：Experimental Design and Method Selection:
Time- and energy-resolved photoemission electron microscopy (PEEM) was used to study ultrafast electron dynamics.
2：Sample Selection and Data Sources:
Monolayer WS2 samples on p-Si and hBN substrates were prepared and characterized.
3：List of Experimental Equipment and Materials:
A high-resolution low-energy electron microscopy (LEEM)/PEEM system equipped with an aberration corrector and imaging energy analyzer was used.
4：Experimental Procedures and Operational Workflow:
Pump-probe measurements were performed with femtosecond laser pulses to excite and probe electron dynamics.
5：Data Analysis Methods:
Electron energy distribution curves (EDCs) were analyzed using Fermi–Dirac distributions to determine electronic temperatures and decay times.
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