研究目的
Investigating the electronic properties and acceptor levels of carbon vacancy defects in 4H-SiC using combined experimental and theoretical methods.
研究成果
The study confirms the connection between Z1 and Z2 traps and carbon vacancies at hexagonal and pseudo-cubic sites in 4H-SiC, with negative-U ordering and specific acceptor levels. Direct capture cross section measurements show minimal barriers, supporting strong coupling in transitions. Mechanisms for electron capture are proposed based on experimental and theoretical results.
研究不足
The study is limited to n-type 4H-SiC and specific defect transitions; error bars for calculated capture barriers are around 0.1 eV, and quantitative accounts for population ratios are speculative due to approximations in theory.
1：Experimental Design and Method Selection:
The study combines Laplace deep level transient spectroscopy (L-DLTS) with density functional modeling to resolve and characterize the Z1/2 peak in 4H-SiC, focusing on electron emission and capture processes.
2：Sample Selection and Data Sources:
Schottky barrier diodes (SBDs) were fabricated from epitaxially grown n-type 4H-SiC layers doped with nitrogen (up to 5×101? cm?3).
3：List of Experimental Equipment and Materials:
Equipment includes a DLTS system, L-DLTS setup, current-voltage (I-V) and capacitance-voltage (C-V) measurement tools, nickel for Schottky and Ohmic contacts, and a Vienna Ab-initio Simulation Package (VASP) for theoretical calculations.
4：Experimental Procedures and Operational Workflow:
DLTS and L-DLTS measurements were performed in the temperature range 100–420 K with specific biases and pulse widths. Capture kinetics were studied with varying pulse widths. Theoretical calculations involved structural optimization and configuration coordinate diagrams using VASP.
5：Data Analysis Methods:
Data were analyzed using Arrhenius plots for emission rates, least-square fitting for DLTS spectra, and harmonic fitting for potential energy curves in theoretical models.
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