A semiconductor device includes a substrate, and a first transistor disposed on the substrate. The first transistor includes a first channel layer, a magnesium oxide layer, a first gate electrode, a first gate dielectric and first source/drain electrodes. A crystal orientation of the first channel layer is <100> or <110>. The magnesium oxide layer is located below the first channel layer and in contact with the first channel layer. The first gate electrode is located over the first channel layer. The first gate dielectric is located in between the first channel layer and the first gate electrode. The first source/drain electrodes are disposed on the first channel layer.

A method of processing a composite structure including a thin layer of single-crystal silicon carbide disposed on a polycrystalline silicon carbide carrier substrate, includes, after formation of electronic component elements on a front face of the composite structure, grinding a rear face of the composite structure and removing a work-hardened layer present on the surface of the rear face as a result of the grinding process.