Patent ID: 8134168

Claim:
A Group III nitride semiconductor element comprising a substrate; a first nitride semiconductor layer composed of AlN single crystal having a thickness of 0.005 to 0.5 μm which is provided on the substrate; a second nitride semiconductor layer composed of Al x1 Ga 1-x1 N(0<x1≦0.05) which is provided on the first nitride semiconductor layer; a third nitride semiconductor layer composed of Al x2 Ga 1-x2 N(x1+0.02≦x2≦0.5) which is provided on the second nitride semiconductor layer; and a fourth nitride semiconductor layer which is provided on the third nitride semiconductor layer, the fourth nitride semiconductor layer including: an n-type contact layer composed of Al a Ga 1-a N (0<a<1), an n-type cladding layer composed of Al b Ga 1-b N (0<b<0.4) which is provided on the n-type contact layer, and a light-emitting layer which has a multiple quantum well (MQW) structure including a well layer composed of Ga 1-s In s N (0<s<0.1) and a barrier layer composed of Al c Ga 1-c N c (0≦c<0.3 and c<b) doped with Si, and is provided on the n-type cladding layer.