Method for reducing silicon carbide crystal impurities and obtaining high-purity semi-insulating silicon carbide crystal

The invention discloses a method for reducing silicon carbide crystal impurities and obtaining a high-purity semi-insulating silicon carbide crystal, and solves the difficult problem of low-impurity high-purity silicon carbide crystal production. The method comprises the following steps: step one, binding a seed crystal onto a graphite support (1), and reversely placing the seed crystal (4) on the top part of a crucible, placing SiC high-purity powder (3) on the bottom part of a growth chamber, wherein the distance from the powder to the seed crystal is about 50 to 60mm; step two, during growing, the periphery of the crucible is subjected to insulation treatment by using graphite felt, the top part and the bottom part of the crucible are respectively provided with a 10 to 20 millimeter heat emission hole to obtain a proper axial temperature gradient, and meanwhile, the holes are used for measuring the temperature in the growth chamber by using a high-temperature infrared instrument. The method provided by the invention aims at obtaining a high-purity silicon carbide crystal through reducing impurity element concentration in the background.