Transparent electrode
A transparent electrode for use in a gallium nitride-based compound semiconductor light-emitting device having an emission wavelength of 440 nm or less, includes a metal layer disposed in contiguity to a p-type semiconductor layer and a current diffusion layer disposed on the metal layer. The transparent electrode contains substantially no Au in the whole region thereof. The metal layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component. The current diffusion layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component except for the case where the metal layer and the current diffusion layer have the same composition. It is possible to provide a white light-emitting device provided with the transparent electrode, a white light-emitting lamp using the white light-emitting device and a lighting fixture using the white light-emitting lamp.
1. A transparent electrode for use in a gallium nitride-based compound semiconductor light-emitting device having an emission wavelength of 440 nm or less, comprising a transparent metal layer disposed in contiguity to a p-type semiconductor layer and a transparent current diffusion layer disposed on the transparent metal layer, the transparent electrode containing substantially no Au in a whole region thereof, the transparent metal layer containing at least one metal selected from the group consisting of Pt, Ir, Ru and Rh as a main component, and the transparent current diffusion layer containing at least one metal selected from the group consisting of Ir, Ru and Rh as a main component, with the proviso that the transparent metal layer and the transparent current diffusion layer do not have the same composition.
2. A transparent electrode according to claim 1 , wherein the emission wavelength is in a range of 300 nm to 440 nm.
3. A transparent electrode according to claim 1 , wherein the transparent electrode contains Pt as a main component in a region contiguous to the p-type semiconductor layer.
4. A transparent electrode according to claim 1 , wherein the transparent metal layer has Pt as a main component.
5. A transparent electrode according to claim 1 , wherein the transparent metal layer has a film thickness in a range of 0.1 to 20 nm.
6. A transparent electrode according to claim 1 , wherein the transparent current diffusion layer has a thickness in a range of 1 to 20 nm.
7. A transparent electrode according to claim 1 , wherein light transmitted through the transparent electrode is 60% or more of incident light.
8. A white light-emitting device provided with the transparent electrode according to claim 1 .
9. A white light-emitting lamp using the white light-emitting device according to claim 8 .
10. A lighting fixture using the white light-emitting lamp according to claim 9 .
11. A transparent electrode according to claim 1 , wherein the transparent current diffusion layer has a lower specific resistance than that of the transparent metal layer.