Nitride semiconductor light emitting device

A nitride semiconductor light emitting device comprising:

• an n-type nitride semiconductor layer provided on a substrate;
• an active layer provided on the n-type nitride semiconductor layer, and including quantum barrier layers and a plurality of quantum well layers;
• and
• a p-type nitride semiconductor layer provided on the active layer,
• wherein each of the quantum barrier layers comprises two InxGa(1-x)N layers (0<x<1) having energy band gaps larger than the quantum well layers and at least three AlyGa(1-y)N layers (0≦y<1) having energy band gaps larger than the two InxGa(1-x)N layers, the at least three AlyGa(1-y)N layers is are stacked between the two InxGa(1-x)N layers and the two InxGa(1-x)N layers are outermost layers of each of the quantum barriers and are adjacent to two of the plurality of quantum well layers and
• wherein the plurality of quantum well layers are formed of InzGa(1-z)N (0<x<z<1),
• each of the two InxGa(1-x)N layers and the at least three AlyGa(1-y)N layers forming the quantum barrier layer has a thickness of 0.5 to 10 nm, and
• a first one of the at least three AlyGa(1-y)N layers has a larger bandgap than that of a second one of the at least three AlyGa(1-y)N layers that is closer to the quantum well layers than the first one of the at least three AlyGa(1-y)N layers.