Abstract: Provided are a high quality silicon carbide seed crystal, a silicon carbide crystal, a silicon carbide substrate, and a preparation method therefor. A high quality silicon carbide seed crystal is prepared, the dopant concentrations of a thermal insulation material, a graphite crucible, and a silicon carbide powder material are controlled, a specific crystal growth process and a wafer machining means are integrated, and a high quality silicon carbide substrate is obtained. The obtained silicon carbide substrate has a high crystalline quality and an extremely low amount of micropipes, screw dislocation density, and compound dislocation density; said substrate also has an extremely low p-type dopant concentration, exhibits superior electrical performance, and has a high surface quality.

Abstract: A silicon carbide single crystal wafer and a preparation method therefor, a silicon carbide crystal and a preparation method therefor, and a semiconductor device. The surface of the silicon carbide single crystal wafer is such that an included angle between a normal direction and a c direction is 0-8 degrees, and aggregated dislocations on the silicon carbide single crystal wafer are less than 300/cm2; the aggregated dislocation is a dislocation aggregated condition in which the distance between the geometric centers of any two corrosion pits in the corrosion pits obtained after corrosion of melted KOH is less than 80 microns. Even if the dislocation density is relatively high, the aggregated dislocation density is relatively small, thereby increasing the yield of a silicon carbide-based devices.