Patent ID: 7667226

Claim:
A semiconductor device made of nitride semiconductor comprising: an active layer having a quantum well structure including a well layer and a barrier layer; a first conductivity type layer and a second conductivity type layer, the active layer being sandwiched between the first conductivity type layer and the second conductivity type layer; wherein a first barrier layer is provided on the side of the first conductivity type layer in the active layer and a second barrier layer is provided on the side of the second conductivity type layer in the active layer, at least one well layer is sandwiched therebetween, and the second barrier layer is physically in contact with the well layer, and the second barrier layer has a band gap energy lower than that of the first barrier layer, and the second barrier layer is larger in thickness than the first barrier layer, and the second barrier layer is located at the most outside position in the active layer, and the second conductivity type layer includes a carrier confinement layer having a band gap energy higher than that of the first barrier layer, the carrier confinement layer being located at a distance of 100 nm or less from the active layer.