Materials Science Forum Vols. 740-742

Abstract: Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

Abstract: The structural defects in the single 6H-SiC crystals grown by the PVT method have been studied by the scanning electron microscopy, Raman scattering and photoluminescence techniques. The formation mechanism of the defects, micropipes and parasitic polytypes 4H and 15R, observed in the single 6H-SiC crystal has been proposed.

Abstract: The growth process of silicon carbide crystals by physical vapor transport (PVT) on Si-face (0001) on-axis 6H-SiC substrates was analyzed. The growth rate was observed to be almost inversely proportional to the deposition pressure (R ∝ p-1) meaning that the growth rate is not limited by the number of growth spirals but by the vapor phase transport of the depositing species from the source to the sample surface. Analysis of the spiral step width shows an inverse square root dependence on the growth rate (y0 ∝ R-½). This experimental result is in accordance with the Burton, Cabrera and Frank theory and hence it can be concluded that there is no back-stress effect present.

Abstract: Ballistic and diffusive growth regimes in the Fast Sublimation Growth Process of silicon carbide can be determined using suggested theoretical model for the mean free path calculations. The influences of temperature and inert gas pressure on the mass transport for the growth of epitaxial layers were analyzed theoretically and experimentally.

Abstract: The study compared the influences of silicon materials from different sources on the crystal growth process and geometry of silicon carbide (SiC). As revealed by the results of the study, although the purity of commercial silicon material was as high as 11N, the rate of crystal growth was slow. However, if the silicon material made by electron beam refining metallurgical silicon was utilized for the SiC crystal growth experiment, the morphology of SiC crystal was better and the rate of crystal growth was faster despite its purity being only about 4.5N.

Abstract: The distribution of extended defects in silicon carbide (SiC) crystals grown on profiled seeds by the sublimation (physical vapor transport) method has been studied by optical microscopy in combination with chemical etching. It is established that free lateral growth on protruding relief elements (mesas) is accompanied by a sharp decrease in the density of threading dislocations and micropipes. The decreased density of dislocations is retained after growing a thick layer that involves the overgrowth of grooves that separated individual mesas.

Abstract: 4H-SiC single crystal with 3-inch diameter was grown by top seeded solution growth (TSSG) technique. We used a new convection control member called “Immersion Guide (IG)” which causes the high and homogenous fluid flow in the solution. As a result, we achieved relatively high growth rate and morphological stability

Abstract: The growth kinetics of SiC crystals doped with Al and Ga impurities and grown by the sublimation sandwich method at a small spacing between the source and the seed (<1 mm) has been studied. Dependence of an Al-doped SiC crystals growth rate on the clearance is shown to be non-monotonic and exhibits maximum at the clearance about of 100-300 μm. Such dependence is also observed for growth of pure and Ga-doped SiC crystals but only on (0001)Si face. The derived dependencies suggest that there are some considerable kinetic limitations of the SiC growth rate. High quality SiC crystals with such high concentration of the Al impurity as 2x10²¹ cm^-3 were grown.

Abstract: In this study, we have investigated the rate-limiting process of 4H-SiC solution growth using Si-Cr based melt, and have tried high-speed growth. It is revealed that the rate-limiting process of SiC growth under our experimental condition is interface kinetics, which can be controlled by such factors as temperature and supersaturation of carbon. By enhancing the interface kinetics, SiC crystal has been grown at a high rate of 2 mm/h. The FWHM values of X-ray rocking curves and threading dislocation density of the grown crystals are almost the same as those of seed crystal. Possibility of high-speed and high-quality growth of 4H-SiC has been indicated.

Abstract: The present research was focused to investigate the effect of internal crucible design that influenced the 4H-SiC crystal growth onto a 6H-SiC seed by PVT method. The crucible design was modified to produce a uniform radial temperature gradient in the growth cell. The seed attachment was also modified with a use of polycrystalline SiC plate. The crystal quality of 4H-SiC single crystals grown in modified crucible and grown with modified seed attachment was revealed to be better than that of crystal grown in conventional crucible. The full width at half maximum (FWHM) values of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 285 arcsec, 134 arcsec and 128 arcsec, respectively. The micropipe density (MPD) of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 101ea/cm^2, 81ea/cm^2 and 42ea/cm^2, respectively.