Evaluation of Unintentionally Doped Impurities in Silicon Carbide Substrates Using Neutron Activation Analysis

Impurity atoms in a high-purity semi-insulating 4H-SiC substrate fabricated by sublimation and an n-type 3C-SiC substrate fabricated by Chemical Vapor Deposition (CVD) were evaluated by neutron activation analysis. Cr, Fe, Zn, As, Br, Mo, Sb, Eu, Yb, Hf, Ta, W and Au atoms were detected in the 4H-SiC fabricated by sublimation. In the 3C-SiC fabricated by CVD, Cr, Zn, As, Br, Mo, Sb, La Sm and Hf atoms were found. The concentration of these atoms tends to decrease with increasing atomic number.