Gallium nitride-based compound semiconductor light-emitting device
A gallium nitride-based compound semiconductor light-emitting device including a positive electrode having openings, which is excellent in light extraction efficiency. The gallium nitride-based compound semiconductor light-emitting device includes a substrate; an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, the layers being formed of a gallium nitride-based compound semiconductor and being stacked in this order on the substrate; a positive electrode which is provided so as to contact the p-type semiconductor layer; and a negative electrode which is provided so as to contact the n-type semiconductor layer, where the positive electrode is a positive electrode having openings, and at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surface derived from spherical particulates.
1. A gallium nitride-based compound semiconductor light-emitting device comprising a substrate; an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, the layers being formed of a gallium nitride-based compound semiconductor and being stacked in this order on the substrate; a positive electrode which is provided so as to contact the p-type semiconductor layer; and a negative electrode which is provided so as to contact the n-type semiconductor layer, wherein the positive electrode is a positive electrode having openings, and at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surfaces whose apical portions are semispherical,
wherein a density of protruding portions (particulates) of the roughened surface is from 1×10 5 pieces/mm 2 to 1×10 8 pieces/mm 2 .
2. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein the positive electrode having the openings is in a lattice pattern or a comb-like pattern.
3. The gallium nitride-based compound semiconductor light-emitting device according to claim 2 , wherein widths of bars of the lattice pattern or teeth of the comb-like pattern are from 1 pm to 50 pm.
4. The gallium nitride-based compound semiconductor light-emitting device according to claim 2 , wherein a distance between bars of the lattice pattern or teeth of the comb-like pattern is from 1 pm to 50 gm.
5. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein diameters of protruding portions (particulates) of the roughened surface are from 0.01 to 3 μm.
6. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein heights of upper ends of the roughened surface are from 0.1 to 2 μm from a surface at which the negative electrode is formed.
7. The gallium nitride-based compound semiconductor light-emitting device according to claim 6 , wherein the heights of upper ends of the roughened surface are the same height as the surface of the p-type semiconductor layer.
8. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein heights of the protruding portions of the roughened surface are from 0.01 to 1 μm.
9. A lamp comprising the gallium nitride-based compound semiconductor light-emitting device according to claim 1 .
10. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein the roughened surface also exists at four sides of the light-emitting device.
11. The gallium nitride-based compound semiconductor light-emitting device according to claim 1 , wherein the roughened surface also exists between the positive electrode and the negative electrode.
12. A method for manufacturing a gallium nitride-based compound semiconductor light-emitting device, comprising the following steps (1) to (4) of:
(1) stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer which are formed of a gallium nitride-based compound semiconductor, in this order on a substrate;
(2) forming a positive electrode having openings on the p-type semiconductor layer;
(3) forming a mask formed of metal microparticles on the p-type semiconductor layer corresponding to the openings; and
(4) performing dry etching onto the gallium nitride-based compound semiconductor from above the mask so that at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surfaces whose apical portions are semispherical,
wherein a density of protruding portions (particulates) of the roughened surface is from 1×10 5 pieces/mm 2 to 1×10 8 pieces/mm 2 .
13. The method according to claim 12 , wherein the step (3) comprises the step of forming a metal thin film on the p-type semiconductor layer and the step of a thermal treatment thereafter.
14. The method according to claim 12 , wherein the metal microparticles are made of metal selected from the group consisting of Ni, Au, Sn, and Ge, or a low melting point alloy containing at least one kind of these metals.
15. A gallium nitride-based compound semiconductor light-emitting device manufactured by the method according to claim 12 .
16. An electronic equipment incorporating the lamp according to claim 9 .
17. A mechanical device incorporating the electronic equipment according to claim 16 .