Patent ID: 7009218

Claim:
A nitride semiconductor device comprising: a semiconductor layer; a first electrode for establishing an ohmic contact disposed on the semiconductor layer, the first electrode including an upper layer and a lower layer and being subjected to heat treatment; and a second electrode formed on the first electrode, the second electrode having a different shape from a shape of the first electrode, the second electrode further including an upper layer and a lower layer, wherein the upper layer of the first electrode consist of an elemental metal, a compound or alloy including at least one of Pt, Pd, Rh, Ir, Ru and Os and the lower layer of the second electrode consists of an elemental metal, a compound or alloy including at least one of Pt, Pd, Rh, Ir, Ru and Os and form a joint region joining the first electrode to the second electrode and at least one of materials forming the upper layer of the first electrode and at least one of materials forming the lower layer of the second electrode are the same.