Evaluation of Trace Impurities in the Preparation of High-Purity Silicon Carbide

Silicon carbide single crystals of high purity have been prepared using a closed cavity sublimation technique. Trace concentrations of compensating acceptor impurities were diminished by high‐temperature degassing of the charge before sublimation. Crystals prepared in this manner were n‐type with an excess donor concentration of about 10 17 cm −3 . In the purest crystals the electron mobility was near 500 cm 2 /v sec at room temperature, reaching a peak value of about 1750 cm 2 /v sec at 92°K.