Optimization of structural perfection of 4H-polytype silicon carbide ingots

Abstract

The degree of structural perfection of 4H-polytype silicon carbide ingots grown by the modified Lely method was improved using a multistage process with sequential change in the seed orientation (similar to the previously suggested RAF process). The grown ingots 20–40 mm in diameter are characterized by an almost total absence of peripheral low-angle boundaries and a significant decrease in the micropore density (two-three orders of magnitude in comparison with the starting material). Repeated shouldering of obtained seeds with (000\( \bar 1 \))C orientation up to 50–55 mm in diameter results in insignificant deterioration of the structural quality in newly formed peripheral regions of the ingot. High-quality perfect silicon carbide wafers were obtained, characterized by a micropore and basal dislocation densities of 5–40 and 103–104 cm−2, respectively.