A semiconductor device with a trench gate structure in a semiconductor body with a hexagonal crystal lattice is disclosed. In an embodiment a semiconductor device includes a semiconductor body with a hexagonal crystal lattice, wherein a mean surface plane of a first surface of the semiconductor body is tilted with respect to a crystal direction of the hexagonal crystal lattice by an off-axis angle, a trench gate structure extending into the semiconductor body and at least two transistor mesas formed from portions of the semiconductor body and adjoining the trench gate structure, wherein sidewalls of the at least two transistor mesas are aligned with a (11-20) crystal plane and deviate from a normal to the mean surface plane by at most 5 degrees, and wherein each transistor mesa comprises a MOS gate channel.