Effects of the Temperature Gradient Near the Crystal‐Melt Interface in Top Seeded Solution Growth of SiC Crystal

Abstract

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.

Flow modification enhancing the growth rate in top seeded solution growth of SiC crystals

“…Hence, the global uid ow was assumed to be determined by electromagnetic convection. However, as reported in our previous study, [17][18][19][20] the crystal growth is affected signicantly by the subsurface ow near the seed crystal. This suggests that the Marangoni convection and centrifugal forced convection had also contributed to the crystal growth together with electromagnetic convection.…”

Numerical Investigation of Thermal Buoyancy, the Electromagnetic Force and Forced Convection in Conventional RF Systems for 4-Inch Sic by TSSG

“…where g is the gravity, β is the thermal expansion coefficient, T is deduced from the Si solution, T crystal = 1970 K, h is the height of the liquid, ν is the kinematic viscosity, and κ is the thermal diffusivity. For the calculation of the area mesh, we refer to the work of Yamamoto [8] and Ha [18,19]. The mesh is more refined in the flow area; the number of grids in the fluid region is 15,000, and the finest grid-scale is 0.5 mm at the seed-solution interface.…”

Effect of Hot-zone Aperture on the Growth Behavior of SiC Single Crystal Produced via Top-seeded Solution Growth Method

“…To investigate the temperature profile, mass transport, and fluid flow in the TSSG reactor, finite element analysis simulations based on electromagnetic and mass and heat transfer analyses were carried out using COMSOL Multiphysics package. 10) The hot-zone structure of the TSSG reactor with a short insulator, which was used to investigate the effect of the length of the graphite insulator in our previous study, 9) was chosen as the reference model in this study. The hot-zone model is shown in Fig.…”

“…The physical theory and calculation details are described elsewhere. 7,9,11,12) All the materials used in the simulation are shown in Fig. 1, and their properties are listed in Table 1.…”

“…In order to investigate the growth rate and quality of SiC crystals grown via the TSSG method, Ha et al proposed an approach to control the temperature gradient in the melt and investigated the effect of temperature gradient especially near the melt-crystal interface. 9) Though the reports on the effect of the aperture of the hot-zone on the growth of SiC crystals via the TSSG method are scarce, we believe that the control of the aperture on the hot-zone can provide a precise control of the temperature gradient in the reactor to obtain high-quality SiC with a reasonable growth rate. Hence, in order to determine the optimal temperature ggradient for balancing the growth rate and crystal quality, we further investigated (both theoretically and experimentally) the temperature gradient in the reactor by changing the aperture of the hotzone.…”