Electron paramagnetic resonance of electronic-grade SiC substrates

Abstract

Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool to study thephysical and chemical structure of point defects in crystalline semiconductors.Investigations throughout the past few decades have provided detailed descriptions of someof the most important intrinsic defects and impurities in silicon carbide. Several reviewshave summarized the significant findings. This review expands the scope of earlier work byfocusing on EPR studies of as-grown electronic grade SiC. Because the mostrecent technological interests focus on growing high-resistivity substrates for highfrequency, high power devices, many of the defects discussed here are identifiedin semi-insulating 4H SiC. The access to high purity material has enabled theidentification of at least one new centre, the positively charged carbon vacancy, whilethe detailed electronic structure of the others is still uncertain. Intentional andunintentional impurities also play a role. For this reason, vanadium and someshallow impurities will be briefly reviewed. Finally, the structure and chemistry ofcarbon-related defects thought to be located near the surface of SiC will be summarized.