High resistivity uniformity of n-type 4H-SiC substrates grown by PVT method

Abstract

6-inch n-type 4H-SiC bulk crystals were grown on 4° off-axis seeds by the physical vapor transport (PVT) method. In general, the resistivity of faceted area is relatively low due to the higher concentration of nitrogen atoms compared with non-faceted area, resulting in resistivity nonuniformity on the whole substrate. The 4H-SiC crystal without facet was grown in slightly concave temperature field and then processed into substrates. Raman spectra data show a more uniform distribution of carrier concentration in the plane of the substrate without facet. The resistivity data show that the difference between the highest and lowest values of resistivity of the entire substrate is less than 1 mΩ•cm, and the resistivity heterogeneity is less than 1%. Meanwhile, the substrate without facet has a lower basal plane dislocation (BPD) density.