A semiconductor device includes trench gate structures extending from a first surface into a semiconductor body from a wide-bandgap semiconductor material. The trench gate structures separate mesa portions of the semiconductor body from each other. In the mesa portions, body regions form first pn junctions with a drain structure and directly adjoin first mesa sidewalls. Source regions in the mesa portions form second pn junctions with the body regions, wherein the body regions separate the source regions from the drain structure. The source regions directly adjoin the first mesa sidewalls and second mesa sidewalls opposite to the first mesa sidewalls.