Patent ID: 6838705

Claim:
A nitride semiconductor device, comprising: a) a substrate; b) an active layer having a multiple quantum well structure containing In a Ga 1−a N (0≦a<1); c) an n-region nitride semiconductor layer structure interposed between said substrate and said active layer, said n-region nitride semiconductor layer structure including, an n-type contact layer, a first n-region multi-film layer which has an undoped lower-film, a middle film doped with an n-type impurity having a thickness within 150 Å-400 Å, and an undoped upper film, said first n-region multi-film layer being positioned between said n-type contact layer and said active layer, d) a p-region nitride semiconductor layer structure on said active layer, said p-region nitride semiconductor layer structure including, a p-type cladding layer, a p-type low-doped layer on said p-type cladding layer, having a concentration of the p-type impurity which is lower than that of said p-type cladding layer; and a p-contact layer formed on said p-type low-doped layer, having a concentration of the p-type impurity which is higher than that of said p-type low-doped layer.