Patent ID: 7880199

Claim:
A semiconductor device comprising: a substrate region; a drain region of a predetermined electroconduction type formed on the substrate region; a hetero semiconductor region contacted with a first main surface of the drain region and comprising a semiconductor material having a bandgap different from that of the drain region; a gate electrode formed through a gate insulator layer at a position adjacent to a junction region between the hetero semiconductor region and the drain region; a source electrode connected to the hetero semiconductor region; and a drain electrode connected to the drain region; wherein the hetero semiconductor region includes a contact portion contacted with the source electrode, at least a partial region of the contact portion is of the same electroconduction type as the electroconduction type of the drain region, and the partial region has an impurity concentration higher than an impurity concentration of at least a partial region of a gate-electrode facing portion in the hetero semiconductor region which is positioned to face toward the gate electrode through the gate insulator layer, the partial region of the gate-electrode facing portion has the same electroconduction type as the electroconduction type of the drain region.