Patent ID: 7709848

Claim:
A group III nitride semiconductor light emitting device comprising: a substrate; an n-type nitride semiconductor layer formed of group III nitride semiconductor containing an n-type impurity on the substrate and including an n-type cladding layer; an active layer for generating light, the active layer being formed on the n-type nitride semiconductor layer and having a smaller bandgap energy than that of the n-type cladding layer; an intermediate layer formed of undoped Al x Ga 1-x-y In y N (0<x<1, 0<y<1, x+y<1) over the active layer; an electron blocking layer formed of p-type group III nitride semiconductor having a smaller electron affinity and a larger Al composition than those of the intermediate layer, and formed directly on the intermediate layer; and a p-type nitride semiconductor layer formed of group III nitride semiconductor containing a p-type impurity on the electron blocking layer and including a p-type cladding layer having a larger bandgap energy than that of the active layer, wherein the electron blocking layer has a largest Al composition among p-type layers included in the light emitting device, and wherein a value obtained by dividing a difference between a lattice constant of the intermediate layer in an a-axis direction in a lattice relaxed state and a lattice constant of the electron blocking layer in the a-axis direction in a lattice relaxed state by the lattice constant of the electron blocking layer in a lattice relaxed state is 0.004 or less.