  The dielectric breakdown (BD) of thermal oxide (SiO2) grown on cubic silicon
carbide (3C-SiC) was investigated comparing the electrical behavior of
macroscopic metal-oxidesemiconductor (MOS) capacitors with nanoscale current
and capacitance mapping using conductive atomic force (C-AFM) and scanning
capacitance microscopy (SCM). Spatially resolved statistics of the oxide BD
events by C-AFM revealed that the extrinsic premature BD is correlated to the
presence of peculiar extended defects, the anti-phase boundaries (APBs), in the
3C-SiC layer. SCM analyses showed a larger carrier density at the stacking
faults (SFs) the 3C-SiC, that can be explained by a locally enhanced density of
states in the conduction band. On the other hand, a local increase of minority
carriers concentration was deduced for APBs, indicating that they behave as
conducting defects having also the possibility to trap positive charges. The
results were explained with the local electric field enhancement in
correspondence of positively charged defects.
