The structural defect effect of impurities on silicon carbide (SiC) was studied to determine the luminescence properties with temperature-dependent photoluminescence (PL) measurements. Single 4H-SiC crystals were fabricated using three different 3C-SiC starting materials and the physical vapor transport method at a high temperature and 100 Pa in an argon atmosphere. The correlation between the impurity levels and the optical and fluorescent properties was confirmed using Raman spectroscopy, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy (ICP-OES), UV-Vis-NIR spectrophotometry, and PL measurements. The PL intensity was observed in all three single 4H-SiC crystals, with the highest intensities at low temperatures. Two prominent PL emission peaks at 420 and 580 nm were observed at temperatures below 50 K. These emission peaks originated from the impurity concentration due to the incorporation of N, Al, and B in the single 4H-SiC crystals and were supported by ICP-OES. The emission peaks at 420 and 580 nm occurred due to donor–acceptor-pair recombination through the incorporated concentrations of nitrogen, boron, and aluminum in the single 4H-SiC crystals. The results of the present work provide evidence based on the low-temperature PL that the mechanism of PL emission in single 4H-SiC crystals is mainly related to the transitions due to defect concentration.

The top seeded solution growth (TSSG) method is a promising technique for fabricating high-quality silicon carbide (SiC) single crystals. The carbon required to grow SiC is provided by dissolving the graphite crucible in the silicon melt, and the carbon distribution in the silicon melt is governed by various factors. In this study, two hot zone structures are evaluated using the finite element analysis (FEA) simulation, especially for the temperature distribution, the velocity field, and the carbon concentration in the silicon melt. The results of the simulations revealed significant differences between the two hot zone structures in terms of temperature and carbon concentrations, especially near the interface between the crystal and the melt. SiC crystals are experimentally grown to verify the simulation results with the two hot zone structures. The grown crystals are evaluated to study their surface morphology, crystal quality, polytype stability, and dislocation density by using optical microscopy, high-resolution X-ray diffraction, micro-Raman spectroscopy, and chemical etching, respectively. The simulations and experiments suggests that the hot zone structure with a small temperature gradient especially near the interface between the crystal and the melt promotes stable conditions for growing SiC crystals via the TSSG method.

This study indicates that etched microgrooves and ridges on titanium substrata induce both typical and unique time-dependent expression patterns of the osteoblast marker genes and proteins analyzed in this study.

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