The physical and electrical properties of Si/SiC heterojunctions formed by direct wafer bonding are presented. Atomic force microscopy (AFM) and imaging reveal an improved bonding quality when Si wafers are transferred to on-axis substrates as opposed to off-axis epitaxial layers. AFM analysis of the bonded wafer achieves a smoother surface when compared to molecular beam epitaxy-grown Si layers. A reduced roughness of only 5.8 nm was measured for bonded wafers. Current-voltage measurements were used to extract the rectifying characteristics of Si/SiC heterojunctions. These Si layers could lead to improved high quality and reliable SiO2 gate oxides. (C) 2008 The Electrochemical Society.