Positive electrode for compound semiconductor light-emitting device
An object of the present invention is to provide a positive electrode, in which the silver is used, for a compound-semiconductor light-emitting device high in inverse voltage and excellent in stability and productivity. The inventive positive electrode for a compound-semiconductor light-emitting device comprises a reflective layer of a silver alloy.
1. A positive electrode, for a compound-semiconductor light-emitting device having a structure wherein an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer are sequentially crystallized and grown on a substrate, which comprises a reflective layer of silver alloy, wherein the silver alloy contains at least one element selected from the group consisting of neodymium, copper and bismuth, the reflective layer has a contact metal layer in contact with the p-type semiconductor layer, and the contact metal layer contains at least one metal selected from the group consisting of Ir, Rh, Ru and Os or an alloy containing at least one of them.
2. A positive electrode, for a compound-semiconductor light-emitting device according to claim 1 , wherein a content of silver in the silver alloy is in a range from 90 to 99.99 atomic %.
3. A positive electrode, for a compound-semiconductor light-emitting device according to claim 1 , wherein the film thickness of the reflective layer is in a range from 30 to 500 nm.
4. A positive electrode, for a compound-semiconductor light-emitting device according to claim 1 , wherein a thickness of the contact metal layer is in a range from 1 to 30 nm.
5. A compound-semiconductor light-emitting device having the positive electrode according to claim 1 .
6. A compound-semiconductor light-emitting device according to claim 5 , wherein the compound-semiconductor is a gallium nitride-based compound-semiconductor.
7. A lamp comprising the compound-semiconductor light-emitting device according to claim 5 .