Method for fabricating nitride semiconductor, method for fabricating nitride semiconductor device, and nitride semiconductor device

A nitride semiconductor device comprising:

• an active layer made of a first nitride semiconductor formed on a substrate;
• a p-type cap layer made of a second nitride semiconductor formed on the active layer;
• a p-type cladding layer made of a third nitride semiconductor formed on the p-type cap layer;
• and
• a p-type contact layer made of a fourth nitride semiconductor formed on the p-type cladding layer,
• wherein at least one of the p-type cap layer, the p-type cladding layer, and the p-type contact layer has a multilayer structure of one layer made of a first group III nitride and another layer made of a second group III nitride different from the first group III nitride formed on the one layer,
• the one layer includes no aluminum, the another layer includes aluminum, and the density of a p-type dopant in the another layer is higher than the density of a p-type dopant in the one layer, and
• the density of the p-type dopant locally increases in an area of the another layer near the interface with the one layer on the substrate side.