研究目的
Investigating the quenching of the photoluminescence from the divacancy defect in 4H-SiC and understanding the underlying mechanisms through experimental and theoretical approaches.
研究成果
The study concludes that the quenching of the divacancy-related PL is due to the conversion of the divacancy from neutral to negative charge state under excitation below certain photon energies. The experimental results are supported by accurate theoretical calculations of the charge-transfer levels, and a simple dynamical model is proposed to describe the quenching phenomenon.
研究不足
The study is limited to ensemble measurements of divacancies in 4H-SiC, and the quenching dynamics may differ for single divacancy defects. The model assumes only one type of traps, which may not fully capture the complexity of the system in highly doped samples.
1：Experimental Design and Method Selection:
The study combines photoluminescence time-decay measurements with photoluminescence excitation spectroscopy (PLE) and electron paramagnetic resonance (EPR) measurements under similar illumination conditions as the PL experiments.
2：Sample Selection and Data Sources:
Three 4H-SiC samples with different doping levels and irradiation doses were used to study the quenching behavior of the divacancy-related PL.
3：List of Experimental Equipment and Materials:
A tunable Ti-sapphire laser for excitation, a double monochromator (SPEX 1404) for detection, an InGaAsP photomultiplier, and a variable-temperature cryostat operated with liquid helium.
4：Experimental Procedures and Operational Workflow:
PL spectra were recorded at different temperatures and excitation conditions, with and without a repump laser. EPR spectra were measured in darkness and under illumination with a 1030 nm diode laser or a white LED.
5：Data Analysis Methods:
The experimental data were analyzed in conjunction with theoretical ab initio calculations for the charge-transfer levels of the divacancy.
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