Gallium nitride-based semiconductor light emitting device and process for its production

A process for fabrication of a semiconductor light emitting device characterized by comprising an n-type semiconductor layer, a light emitting layer and a p-type semiconductor layer in that order on a substrate, with a negative electrode and positive electrode each formed in contact with the n-type semiconductor layer and p-type semiconductor layer, respectively, wherein the positive electrode comprises at least a contact metal layer composed of at least one type of metal selected from the group consisting of Pt, Ir, Rh, Pd, Ru and Re or their alloy in contact with the p-type semiconductor layer, a reflective layer composed of a metal or alloy containing Ag as the main component on the contact layer, and one or more protective metal layers containing no Ag, completely covering the top and side surfaces of the reflective layer

• wherein the thicknesses of the one or more protective metal layers are between 500 nm and 10 μm;
• and
• wherein an undercoat layer composed of at least one metal selected from among Pt, Ir, Rh, Pd, Ru and Re or an alloy comprising at least one of these metals is formed between the reflective layer and the one or more protective metal layers in contact with the both layers,
• said process characterized by forming an n-type semiconductor layer, a light emitting layer and a p-type semiconductor layer in that order on a substrate, providing a negative electrode and positive electrode in contact with the n-type semiconductor layer and p-type semiconductor layer, respectively, forming as the positive electrode at least a contact metal layer composed of at least one type of metal selected from the group consisting of Pt, Ir, Rh, Pd, Ru and Re or their alloy in contact with the p-type semiconductor layer, and a reflective layer composed of a metal or alloy containing Ag as a component on the contact layer, and forming at least one protective metal layer containing no Ag, completely covering the top and side surfaces of the reflective layer, by a plating process.