Nitride semiconductor element
In the nitride semiconductor device having a p-type nitride semiconductor layer, an electrode including at least rhodium and iridium is formed on the p-type nitride semiconductor layer. By this construction, an excellent ohmic contact between the electrode and the p-type nitride semiconductor layer and a high reflectivity in the electrode can be obtained, so that the nitride semiconductor device having excellent external quantum efficiency can be provided.
1. A nitride semiconductor device comprising:
a p-type nitride semiconductor layer; and
a p-electrode having an at least two-layer structure;
wherein said p-electrode includes a rhodium layer disposed on said p-type nitride semiconductor layer and an iridium layer disposed on the rhodium layer.
2. The nitride semiconductor device according to claim 1 , wherein said p-type nitride semiconductor layer is located below an n-type nitride semiconductor layer.
3. The nitride semiconductor device according to claim 1 , wherein said nitride semiconductor device has a structure of a face-down configuration.
4. The nitride semiconductor device according to claim 1 , further comprising a p-type nitride semiconductor layer disposed on said p-electrode which is disposed in contact with a substrate.
5. The nitride semiconductor device according to claim 1 , wherein light is extracted from at least one of a surface of the substrate and a side surface of said device.
6. The nitride semiconductor device according to claim 1 , wherein said p-electrode has a shape in two dimensions that is selected from the group comprising a rectangle, a stripe, a square, a gird, a shape with dot-shaped hollows, diamond, a parallelogram, a mesh, stripes, comb-shaped, a plurality of branches divided out from a stripe, and a circle.
7. The nitride semiconductor device according to claim 1 , wherein in said p-electrode, a thickness of the rhodium layer is from 10 angstroms to 1000 angstroms.
8. The nitride semiconductor device according to claim 1 , wherein in said p-electrode, a thickness of the iridium layer is from 10 angstroms to 1000 angstroms.
9. The nitride semiconductor device according to claim 1 , wherein in said p-electrode, a thickness of the rhodium layer is from 10 angstroms to 1000 angstroms and a thickness of the iridium layer is from 10 angstroms to 1000 angstroms.
10. The nitride semiconductor device according to claim 1 , wherein said p-electrode is annealed at a temperature of at least 300° C.