Patent ID: 8791505

Claim:
A semiconductor device comprising: a first nitride semiconductor layer; a second nitride semiconductor layer formed on the first nitride semiconductor layer, and having a larger band gap than the first nitride semiconductor layer; and an ohmic electrode formed to fill a recess which passes through the second nitride semiconductor layer, and is formed such that the first nitride semiconductor layer is recessed, wherein a two-dimensional electron gas layer is formed in a portion of the first nitride semiconductor layer immediately below an interface between the first and second nitride semiconductor layers, the ohmic electrode and the second nitride semiconductor layer are in contact with each other at least a first contact interface being a portion of a side surface of the recess, the ohmic electrode and a portion of the first nitride semiconductor layer corresponding to the two-dimensional electron gas layer are in contact with each other at least a second contact interface being a portion of the side surface of the recess and connected below the first contact interface, the first contact interface is formed such that a width of the recess increases from a lower surface of the second nitride semiconductor layer to an upper surface thereof, and the second contact interface is more steeply inclined with respect to a top surface of the first nitride semiconductor layer than the first contact interface in a vicinity of a joint between the first and second contact interfaces.