研究目的
Investigating the ultrafast dynamics of photoexcited carriers in β-Ga2O3 using two-color optical pump-probe spectroscopy to understand carrier recombination via defect-assisted processes.
研究成果
The study provides insights into the mechanisms and rates of carrier capture by defects in β-Ga2O3, highlighting a temperature-independent electron capture rate and a temperature-dependent hole capture rate. The findings are significant for the development of high-voltage and high-speed transistors and photodetectors based on β-Ga2O3.
研究不足
The study is limited to the dynamics occurring within approximately 1 ns due to the maximum pump-probe delay limited by the mechanical delay stage. The model assumes midgap defect states are well separated in energy from band edges, ignoring carrier emission from defects.
1：Experimental Design and Method Selection:
A two-color optical pump-probe spectroscopy setup was used to photoexcite carriers in β-Ga2O3 via a two-photon absorption process and probe the subsequent dynamics using free-carrier absorption of a near-IR probe pulse.
2：Sample Selection and Data Sources:
Bulk β-Ga2O3 samples, grown by the edge-defined film-fed growth (EFG) technique, were used.
3：List of Experimental Equipment and Materials:
A Ti:Sapphire laser for generating pump and probe pulses, mechanical delay stage, and lock-in detection for measuring differential transmission.
4：Experimental Procedures and Operational Workflow:
Pump and probe beams were collinearly aligned and linearly polarized at different angles with respect to the crystal axes. The dynamics of photoexcited carriers were recorded as a function of probe delay from the pump.
5：Data Analysis Methods:
A rate equation model for electron and hole capture by defects was developed to analyze the data.
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