Patent ID: 7348602

Claim:
A nitride semiconductor device comprising: an n-type first nitride semiconductor layer; a p-type second nitride semiconductor layer including a p-type cladding layer, a p-type low-doped layer on said p-type cladding layer, the p-type low-doped layer having a concentration of 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, the p-contact layer having a concentration of p-type impurity which is higher than that of said p-type low-doped layer; and an active layer located between said n-type first nitride semiconductor layer and said p-type second nitride semiconductor layer; wherein said n-type first nitride semiconductor layer comprises an n-type contact layer, a first n-region multi-film layer located between said n-type contact layer and said active layer, and a second n-region multi-film layer located between said first n-region multi-film layer and said active layer, wherein said first n-region multi-film layer comprises a lamination of an undoped lower layer, a middle layer doped with an n-type impurity and an undoped upper layer, and wherein said second n-region multi-film layer comprises a lamination of at least three layers, said at least three layers including at least one third nitride semiconductor layer of a nitride semiconductor containing In, and said at least three layers further including at least one fourth nitride semiconductor layer of a composition which is different than that of said third nitride semiconductor layer, and wherein at least one of said third and fourth nitride semiconductor layers has a thickness of 100 Å or less.