In a general aspect, a silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) can include a substrate of a first conductivity type, a drift region of the first conductivity type disposed on the substrate, a spreading layer of the first conductivity type disposed in the drift region, a body region of a second conductivity type disposed in the spreading layer, and a source region of the first conductivity type disposed in the body region. The SiC MOSFET can also include a gate structure that includes a gate oxide layer, an aluminum nitride layer disposed on the gate oxide layer, and a gallium nitride layer of the second conductivity disposed on the aluminum nitride layer.