Investigating positive oxide charge in the SiO2/3C-SiC MOS system

This paper investigates the origin of the fixed positive oxide charge often experimentally observed in Metal Oxide Semiconductor (MOS) structures of SiO2 formed on cubic silicon carbide (3C-SiC). The electrical properties of MOS structures including either thermally grown SiO2 or deposited SiO2 by Plasma Enhanced Chemical Vapour Deposition (PECVD) on epitaxial 3C-SiC layers grown directly on Si are investigated. MOS structures with a range of oxide thickness values subjected to different thermal treatments were studied. It was found that both thermally grown and deposited SiO2 on 3C-SiC exhibit similar positive charge levels indicating that the charge originates from interface states at the 3C-SiC surface and not from the oxide. The nature of this surface charge in the SiO2/3C-SiC system is also discussed based on the current data and previously published results.