Patent ID: 7915607

Claim:
A nitride semiconductor device comprising: an n-type nitride semiconductor layer; a p-type nitride semiconductor layer; and an active layer formed between the n-type and p-type nitride semiconductor layers, wherein the active layer has an alternately-layered structure of a plurality of quantum well layers and a plurality of quantum barrier layers, each alternately stacked on each of the quantum well layers, wherein the alternately-layered structure of a plurality of quantum well layers and a plurality of quantum barrier layers comprises: a plurality of unit multi-layer structure including a first quantum well layer, a second quantum well layer formed adjacent to the first quantum well layer at a position facing the p-type nitride semiconductor layer, the second quantum well layer having a quantum level higher than that of the first quantum well layer, a tunneling quantum barrier layer disposed between the first and second quantum well layers and a crystal quality-improving layer formed adjacent to the second quantum well layer at a position facing the p-nitride semiconductor layer, the crystal quality-improving layer comprising a quantum barrier layer having a thickness greater than that of the tunneling quantum barrier layer; and a thick quantum well formed to be between the unit multi-layer structures, adjacent to the first and second quantum well layers, with a thickness thereof being greater than that of the first and second quantum well layers.