Electrical properties of oxidized polycrystalline silicon as a gate insulator for n-type 4H-SiC MOS devices

Abstract

MOS capacitors were produced on n-type 4H-SiC using oxidized polycrystalline silicon (polyoxide). The polyoxide samples grown by dry oxidation without an anneal had a high interface state density ( D it) of 1.8 × 10 12 cm −2 eV −1 and the polyoxide samples grown by wet oxidation had a lower D it of 1.2 × 10 12 cm −2 eV −1 (both at 0.5 eV below the conduction band). After 1 h Ar annealing, the D it of wet polyoxide was reduced significantly to 2.6 × 10 11 cm −2 eV −1 (at 0.5 eV below the conduction band). Dry polyoxide exhibits higher breakdown electric fields than wet polyoxide. The interface quality and breakdown characteristics of polyoxide are comparable to published results of low-temperature CVD deposited oxides.