Variation of interface trap level charge density within the bandgap of 4H-SiC with varying oxide thickness

Abstract

Interfacial characteristics of metal oxide-silicon carbide (MOSiC) structure with different thickness of SiO2, thermally grown in steam ambient on Si-face of 4H-SiC (0 0 0 1) substrate were investigated. Variations in interface trapped level density (Dit) was systematically studied employing high-low (H-L) frequency C–V method. It was found that the distribution of Dit within the bandgap of 4H-SiC varied with oxide thickness. The calculated Dit value near the midgap of 4H-SiC remained almost stable for all oxide thicknesses in the range of 109–1010 cm−2 eV−1. The Dit near the conduction band edge had been found to be of the order of 1011 cm−2 eV−1 for thicker oxides and for thinner oxides Dit was found to be the range of 1010 cm−2 eV−1. The process had direct relevance in the fabrication of MOS-based device structures.