研究目的
To estimate the band-energy state of silicidation-less ohmic contacts formed by silicon-cap annealing (SiCA) on 4H-SiC using hard X-ray photoelectron spectroscopy (HAXPES) and to understand the ohmic contact formation mechanism.
研究成果
The study demonstrated that SiCA modulates the surface potential energy of SiC, leading to a lowering of the potential barrier and the formation of a thin-depletion layer, which facilitates ohmic contact formation without silicidation annealing. The flexibility of SiCA could improve the reliability of contacts in wide-band-gap semiconductor materials.
研究不足
The study focuses on the surface modification and band-energy estimation of SiCA-processed SiC, but the specific physical surface structure of SiCA-SiC and its detailed impact on ohmic contact formation require further investigation.
1：Experimental Design and Method Selection:
The study involved the use of HAXPES to directly estimate the band-energy state of silicidation-less ohmic contacts formed by SiCA on 4H-SiC. The methodology included the crystallization of an amorphous-Si layer deposited on the Si-face of the SiC wafer and subsequent electrical and spectroscopic characterization.
2：Sample Selection and Data Sources:
Commercially available Si-face (0001) 4° off n-type low resistivity 4H-SiC wafers were used. The samples underwent conventional cleaning, a-Si layer deposition, crystallization via rapid thermal annealing, and Al contact formation.
3：List of Experimental Equipment and Materials:
Equipment included an RF-sputtering system for a-Si deposition, a rapid thermal annealing system, a thermal evaporation system for Al deposition, a Scienta Omicron R-4000 photoelectron analyzer for HAXPES measurements, and a transmission electron microscope for structural analysis.
4：Experimental Procedures and Operational Workflow:
The process involved a-Si layer deposition, crystallization annealing, Al contact formation, I-V characteristics measurement, and HAXPES analysis. The samples were treated with HF acid to remove surface oxide layers before HAXPES measurements.
5：Data Analysis Methods:
Curve fitting was performed to determine peak positions from the obtained HAXPES spectra. The energy band diagram was estimated based on the binding energy shifts observed.
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