Semiconductor power devices having gate dielectric layers with improved breakdown characteristics and methods of forming such devices

A semiconductor device includes a semiconductor layer structure including silicon carbide, a gate dielectric layer on the semiconductor layer structure, and a gate electrode on the gate dielectric layer opposite the semiconductor layer structure. In some embodiments, a periphery of a portion of the gate dielectric layer below the gate electrode is thicker than a central portion of the gate dielectric layer, and a lower surface of the gate electrode has a recessed outer edge, such as a rounded and/or beveled outer edge. 一种半导体设备包括包含碳化硅的半导体层结构、半导体层结构上的栅极介电层，以及栅极介电层上与半导体层结构相对的栅极电极。在一些实施例中，栅极介电层的位于栅极电极下方的部分的外围比栅极介电层的中心部分厚，并且栅极电极的下表面具有凹进的外边缘，诸如倒圆和/或斜切的外边缘。