This paper presents a macro-and nanoscale electrical investigation of Schottky and metal-oxide junctions with hetero-epitaxial 3C-SiC layers grown on Si. Statistical current-density-voltage (JV) characterization of Pt/3C-SiC Schottky diodes showed an increase of the reverse leakage current with increasing the devices diameters. Furthermore, CV and JV analyses of SiO2/3C-SiC capacitors revealed non-idealities of the thermal oxide, such as a high trapped positive charge (3× 1012 cm-2) and a reduced breakdown field (EBD= 6.5 MV/cm) compared to ideal SiO2. Nanoscale electrical characterizations by conductive atomic force microscopy (CAFM) and scanning capacitance microscopy (SCM) allowed to shed light on the origin of non-ideal behavior of Schottky and thermal oxide junctions, by correlating the morphological features associated to 3C-SiC crystalline defects with local current transport and carrier density.