A semiconductor device includes a Schottky diode and a High Electron Mobility Transistor (HEMT) formed on a III-nitride stack. The III-nitride stack includes at least a lower and an upper III-nitride layer forming a heterojunction therebetween, so that a 2-dimensional electron gas (2DEG) layer may be formed in the lower layer. The 2DEG layer serves as a charge carrier for the diode and the HEMT. A doped III-nitride layer may be present between a portion of the anode of the diode and the III-nitride stack, and the portion may be located between the diode's Schottky junction and the cathode. A further layer of doped III-nitride material may be present between the gate electrode of the HEMT and the III-nitride stack. The thickness of the III-nitride layers is not equal, so that the turn-on voltage of the diode and the threshold voltage of the HEMT may be tuned according to specific requirements. The disclosure also involves a method of producing such a semiconductor device.