Patent ID: 7859020

Claim:
A nitride semiconductor device, comprising: a substrate; a stacked semiconductor structure formed over said substrate and including a electron channel layer of an undoped nitride semiconductor and an electron supplying layer of an n-type nitride semiconductor formed epitaxially over said electron channel layer, said n-type nitride semiconductor having an electron affinity smaller than an electron affinity of said undoped nitride semiconductor and a two-dimensional electron gas being formed in said electron channel layer along an interface to said electron supplying layer; a gate electrode formed over said stacked semiconductor structure in correspondence to a channel region; and source and drain electrodes formed over said stacked semiconductor structure in ohmic contact therewith respectively at a first side and a second side of said gate electrode, said stacked semiconductor structure including, between said substrate and said electron channel layer, an n-type conductive layer and a barrier layer containing Al formed consecutively and epitaxially, and an n-type band control layer between said n-type conductive layer and said barrier layer.