Article PreviewArticle PreviewArticle PreviewIn this paper, the electrical properties of a thermal oxide (SiO 2) grown onto 3C-SiC layers on silicon were investigated, by monitoring the behavior of MOS capacitors. In particular, the growth rate of thermal SiO 2 was dependent on the different surface roughness condition. However, independent of the roughness a high density of positive charge was detected. The sample having the smooth surface (subjected to CMP) showed a notably improved dielectric breakdown (BD) field. However, the best BD on macroscopic MOS capacitors was still far from the ideal behavior. Additional insights could be gained employing a nanoscale characterization that revealed the detrimental role of persisting extended defects in the semiconductor. In the semiconductor region far from extended defects the nanoscale BD kinetics was nearly ideal.