Enhancing interface quality by gate dielectric deposition on a nitrogen-conditioned 4H–SiC surface

Using metal-oxide-semiconductor devices, we show that the density of interface states at the SiO2/4H–SiC interface can be reduced by applying a N2heat treatment to a silicon carbide (SiC) surface prior to the deposition of a gate dielectric. Remarkably, this technique yields an interface that is at least as good as the one formed by thermal oxidation in terms of electrically active defects. This improvement can be traced to nitrogen insertion at the semiconductor surface, which provides a seed layer for subsequent deposition. The nature of N incorporation and its impact on electrical properties were studied using x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and capacitance-voltage measurements. These results offer a new perspective in the quest to maximize minority carrier mobility and minimize energy loss in 4H–SiC switches.