Abstract: A semiconductor device comprises a semiconductor body (10) in and on which a power transistor (T; 1, 2, 3) and a suppression diode (D; 100) are integrated. A diode junction (40; 40′) is present between the back metallization (22) and the adjacent region (2) of the power transistor so as to provide the diode in series with this region (2) and adjacent to the back surface (12) of the body. This diode junction (40; 40′) opposes the p-n junction (42) between the collector or drain region (2) of the transistor and its base region (3), so as to suppress reverse current flow in the transistor. The higher doped part (2b) of the adjacent transistor region (2) is sufficiently thick as to prevent any minority charge carriers injected by the diode junction (40; 40′) from reaching the p-n junction (42) with the base region (3). The diode junction may be a p-n junction (40) or a Schottky barrier (40′).