A semiconductor device includes a semiconductor layer structure that includes 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 that underlies the gate electrode is thicker than a central portion of the gate dielectric layer, and a lower surface of the gate electrode has recessed outer edges such as rounded and/or beveled outer edges.