2024, Vol.34, No.2

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

In this study, the resistance characteristics of semi-insulating SiC single crystals grown using the PVT method were investigated, considering the purity level of SiC source powders used in PVT growth and the cooling procedure after crystal growth. Two β-SiC powders with different purities were employed, and the cooling rate after growth was adjusted to achieve various resistance values. 4-inch HPSI-SiC ingots were grown using the PVT method, utilizing SiC powderswith low nitrogen concentration and relatively high nitrogen concentration. These ingots were then subjected to different cooling procedures to modify the cooling rate. Transmission/absorption spectra and crystal quality of the grown crystals were analyzed through UV/VIs/NIR spectroscopy and X-ray rocking curve analysis, respectively. Additionally, electrical properties were investigated through non-contact resistivity analysis to identify the dominant factors influencing resistivity properties.

During the Hg₂Br₂ physical vapor transport process with self-diffusion, it is concluded that for 10-3≤g0≤g≤1g0 the thermal buoyancy driven convection is dominant in the vapor phase; at the gravitational level of g=10-4g0, the transition region from the convection to diffusion occurs; for 10-6g0≤g≤10-5g0, the diffusion mode is predominant. The total molar flux of Hg₂Br₂ decays exponentially with the decreasing of one tenth of gravitational magnitude. For 10°C≤ΔT≤50°C, the total molar flux increases linearly and directly with the temperature difference between the source and crystal regions.

Two-dimensional (2D) RuO₂ nanosheets with nanometer thickness were synthesized using a chemical exfoliation method. The synthesized 2D-RuO₂ was hybridized with Ag-nanowire (NW), which is attracting attention as a next-generation transparent electrode material. After coating Ag-NW on the substrate, 2D-RuO₂ was subsequently coated on the Ag-NW. Although there was a decrease in optical transmittance, the hybridization of 2D-RuO₂ confirmed the effect of reducing sheet resistance. Furthermore, the flexibility of the fabricated transparent electrodes was also studied. It was confirmed by the change in sheet resistance after bending. The additional coating of 2D-RuO2 improved the flexibility of the transparent electrodes.