Nitric Acid Oxidation of 3C-SiC to Fabricate MOS Diodes with a Low Leakage Current Density

Two-step nitric acid oxidation which involves immersion in followed by immersion in at can form a thick (e.g., ) layer on a surface. Heat-treatment at in pure hydrogen performed after nitric acid oxidation greatly decreases the density of the leakage current flowing through the layer. The hydrogen treatment effectively smoothens the interface. When the hydrogen treatment at is performed before nitric acid oxidation, the surface is greatly flattened and the subsequent nitric acid oxidation results in the interface having an atomic flatness. Without hydrogen treatment, gap states are present up to from the valence-band maximum, and the valence-band discontinuity energy at the interface is . With the hydrogen treatment before nitric acid oxidation, the gap states disappear and the valence-band discontinuity energy increases to . Capacitance-voltage curves of the metal-oxide-semiconductor (MOS) diodes in which hydrogen treatment is performed before nitric acid oxidation show typical accumulation and depletion behavior.