Effect of post oxidation annealing on electrical characteristics of Ni/SiO$_2$/4H-SiC capacitor with varying oxide thickness

This paper describes an experimental observation of post oxidation annealing (POA) treatment on current-voltage and capacitance-voltage characteristics of Ni/SiO$_2$/4H-SiC system with varying oxide thickness. The leakage current of fabricated structures shows an asymmetric behavior having noticeable effect of POA with the polarity of gate bias (+V or -V at the anode). When compared with the conventional wet oxidation, the POA processes greatly reduce interface-state density and enhance reliability of devices. An extensive increment in the barrier height at SiO$_2$/4H-SiC interface was observed due to POA, which resulted into lower forward leakage current. A significant improvement in the oxide charges are also demonstrated using C–V characteristics of POA treated structures.