研究目的
Investigating the electron transport properties in GaAs/In0.2Ga0.8As core/shell nanowires at high electric fields using optical pump/THz probe spectroscopy.
研究成果
The study demonstrates that the electron transport in GaAs/In0.2Ga0.8As core/shell nanowires at high electric fields is characterized by intervalley electron scattering, leading to a doubling of the average electron effective mass and a decrease in electron mobility. The increase in effective mass is nonuniform along the nanowires, occurring mainly in their middle part. These findings highlight the potential of GaAs-based nanowires for nanodevices operating at THz frequencies.
研究不足
The study is limited by the difficulty of contacting nanometer-sized devices and the strong heat dissipation caused by the operation in the high-field regime. Additionally, the modeling of the effective mass distribution along the nanowire is simplistic and does not account for a continuous distribution.
1：Experimental Design and Method Selection:
Optical pump/THz probe spectroscopy with broadband THz pulses and peak electric fields up to
2：6 MV/cm was used to probe the electron transport properties. Sample Selection and Data Sources:
Undoped GaAs/In
3：2Ga8As core/shell nanowires with a length of ~2 μm were grown on a Si(111) substrate using molecular beam epitaxy. List of Experimental Equipment and Materials:
The experimental setup included a laser system with a repetition rate of 250 kHz for preliminary characterization and a setup for high-field THz measurements.
4：Experimental Procedures and Operational Workflow:
The near-infrared pump with photon energy of
5：55 eV generates electron-hole plasma in the nanowires. The pump-induced changes in the transmission of the delayed THz probe pulse were recorded for different pump-probe delay times. Data Analysis Methods:
The photoconductivity was calculated using the standard procedure, and the plasmon resonance was fitted with a Lorentzian function to extract parameters such as scattering rate, LSP frequency, and spectral weight.
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