研究目的
To clarify the roles of phonon-assisted donor-acceptor pairs (DAPs) and free-to-acceptor (e-A) emissions in n-type 4H-SiC doped with nitrogen (N) and boron (B) to understand the carrier recombination mechanism and develop fluorescent SiC with a high color rendering index.
研究成果
The D center-related green luminescence in N+B-doped n-type 4H-SiC involves phonon-assisted DAP and e-A recombinations, with DAP emissions decaying faster at low temperatures and e-A emissions dominating at higher temperatures. The hole thermal emission rate is enhanced at high temperatures, accelerating e-A decay. These findings are crucial for designing buffer layers and developing fluorescent SiC for applications like white light-emitting diodes.
研究不足
The paper does not explicitly state limitations, but potential areas include the difficulty in distinguishing overlapping DAP and e-A emissions at certain temperatures and the use of specific doping concentrations and temperatures that may not cover all scenarios.
1：Experimental Design and Method Selection:
Temperature-dependent time-resolved photoluminescence (TRPL) spectral analyses were performed to distinguish phonon-assisted DAP and e-A emissions. The methodology involved using TRPL decay curves and spectral fitting with Voigt profiles to separate the components.
2：Sample Selection and Data Sources:
Epilayers of N+B-doped n-type 4H-SiC with thicknesses of 48–100 μm were grown on 4H-SiC substrates by chemical vapor deposition. Doping concentrations were determined by secondary ion mass spectrometry (SIMS), with N from 7 × 10^17 cm^{-3} to 8 × 10^18 cm^{-3} and B from 2 × 10^16 cm^{-3} to 7 × 10^17 cm^{-3}.
3：3}. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A frequency-tripled Nd:YVO4 laser (wavelength 355 nm, pulse width 5 ns) and a frequency-tripled Nd:YLF laser (wavelength 349 nm) were used as excitation sources. A photonic multichannel analyzer (PMA-12 C10029, Hamamatsu Photonics K.K.) with a digital delay and pulse generator was used for TRPL measurements. A He–Cd laser (wavelength 325 nm) and a Hg–Xe lamp with a 313 ± 20 nm bandpass filter were used for steady-state PL and PL imaging.
4：Experimental Procedures and Operational Workflow:
TRPL decay curves were obtained from 79 to 523 K with a pulse repetition rate of 10 kHz. PL spectra were acquired at various delay times. Microwave photoconductive decay (microwave PCD) measurements were also performed. Steady-state PL spectra from 10 to 523 K and two-dimensional PL images at room temperature were acquired.
5：Data Analysis Methods:
Curve fitting using two Voigt profiles was employed to separate DAP and e-A components in TRPL spectra. Activation energy was estimated from Arrhenius plots of e-A emission intensity.
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