Micro-scale investigation of single crystal SiC anodizing behaviors: Effect of anodizing voltage

Anodizing has been widely applied for processing single crystal SiC as a highly efficient oxidation technique. However, SiC anodizing is considered inhomogeneous. Achieving smooth oxide-SiC interface has not been realized yet. In this study, anodizing was carried out in potassium chloride (KCl) aqueous solution with electric conductivity of 206 mS/cm. The anodizing behaviors, especially changes in the surface and interface morphologies at different voltages have been investigated. Experimental results revealed that anodizing SiC at low and high voltages had different developing mechanisms. At low voltages (10, 14, 16 V), anodizing occurred locally, preferentially oxidized doped or damaged sites and resulted in a rough oxide-SiC interface with a maximum Sq roughness of 16.8 nm. In contrast, anodizing became homogeneous at high anodic voltages (30, 40, 50 V), resulting in a smooth oxide SiC interface with a Sq roughness of 0.58 nm. A possible model was proposed to elucidate the different developing mechanisms and theoretical explanations were given.