Solution Growth on Concave Surface of 4H-SiC Crystal

A long-term growth of high-quality 4H-SiC single crystals by a top-seeded solution growth method using a Si-Cr-based melt was investigated. A new growth technique called "solution growth on concave surface" (SGCS) was developed to help prevent solvent inclusions. The concave shape of the growth surface was achieved by controlling the meniscus height, which enhances the step provision from the periphery to the center. In contrast, under the growth surface, the solution flows from the center to the periphery through convection by inductive heating. The opposite directions of the step flow and solution flow during solution growth create a smooth surface without solvent inclusions. SGCS was used to successfully grow a 1-in. diameter 4H-SiC crystal with a thickness of 30 mm, which is the thickest reported for a solution growth technique, and 1.7-in. diameter high-quality wafers without solvent inclusions were obtained. Schottky barrier diodes were fabricated on 4H-SiC substrates grown by SGCS, which demonstrated breakdown voltages in excess of the 1.2 kV required for hybrid vehicle applications.