Patent ID: 8735195

Claim:
A method for forming a contact electrode for a p-type ZnO-based semiconductor, comprising: (A) forming a doped p-type Mg x Zn (1-x) O layer, wherein 0<x<0.43, as an uppermost layer of the p-type ZnO-based semiconductor layer; (B) forming a contact metal layer on the doped p-type Mg x Zn (1-x) O layer to form a first p-electrode layer, wherein the contact metal layer contains at least one of Ni and Cu, and has a thickness of 60 nm or less; (C) forming a barrier metal layer directly on the contact metal layer to form a second p-electrode layer; (D) forming a pad metal layer on the barrier metal layer to form a third p-electrode layer; and (E) performing a heat treatment, after steps (B), to form a mixture region of the doped p-type Mg x Zn (1-x) O layer and the contact metal layer, wherein the heat treatment is performed under a reductive gas atmosphere containing H 2 and at a temperature in the range of 350 to 450° C. to change the contact metal layer into an oxide layer at the interface of the contact metal layer and the doped p-type Mg x Zn (1-x) O layer, while maintaining a metal phase layer of the contact metal layer on the side of the second p-electrode layer.