Patent ID: 7999286

Claim:
The MIS field-effect transistor comprising: a substrate; a nitride semiconductor multilayer structure portion formed on the substrate, the nitride semiconductor multilayer structure portion including a first group III-V nitride semiconductor layer of a first conductivity type, a second group III-V nitride semiconductor layer of a second conductivity type stacked on the first group III-V nitride semiconductor layer, a third group III-V nitride semiconductor layer of the first conductivity type stacked on the second group III-V nitride semiconductor layer, a fourth group III-V nitride semiconductor layer of the first conductivity type formed between the substrate and the first group III-V nitride semiconductor layer, and a fifth group III-V nitride semiconductor layer formed between the substrate and the fourth group III-V nitride semiconductor layer; a gate insulating film formed on a wall surface formed over the first, second and third group III-V nitride semiconductor layers to extend over the first, second and third group III-V nitride semiconductor layers; a gate electrode made of a conductive material formed as being opposed to the second group III-V nitride semiconductor layer with the gate insulating film interposed therebetween; a drawn portion electrically connected to the first group III-V nitride semiconductor layer and drawn from the nitride semiconductor multilayer structure portion in a direction parallel to the substrate; a drain electrode formed in contact with the drawn portion; and a source electrode electrically connected to the third group III-V nitride semiconductor layer; wherein the source electrode is provided as being in contact with both of the second group III-V nitride semiconductor layer and the third group III-V nitride semiconductor layer.