Semiconductor light emitting device and its manufacturing method
View Patent ↗Efficiency of leading out light released from an active layer, i.e. the external quantum efficiency, can be improved remarkably by processing a light lead-out surface to have an embossment. A layer containing a p-type dopant like magnesium (Mg) is deposited near the surface of a p-type GaN layer to diffuse it there, and a p-side electrode is made on the p-type GaN layer after removing the deposited layer. This results in ensuring ohmic contact with the p-side electrode, preventing exfoliation of the electrode and improving the reliability.
1. A semiconductor light emitting device comprising:
a light emitting portion,
a semiconductor layer formed on said light emitting portion, said semiconductor layer having a first embossment on the surface thereof, and
a transparent electrode formed on said first embossment of said semiconductor layer, said transparent electrode having a second embossment on a surface thereof, said first and second embossment having a cylindrical or hemispherical shape.
2. The semiconductor light emitting device according to claim 1 , wherein said semiconductor layer is doped, at a portion near the interface to said transparent electrode layer, with a dopant of a higher concentration than the other portion.
3. The semiconductor light emitting device according to claim 1 , wherein said transparent electrode includes a layer of a metal having a thickness not thicker than 100 nm and formed in contact with said semiconductor layer.
4. The semiconductor light emitting device according to claim 3 , wherein said metal contains at least one of nickel (Ni) and platinum (Pt).
5. A semiconductor light emitting device comprising:
a light emitting portion,
a semiconductor layer formed on said light emitting portion, wherein said semiconductor layer has an even surface.
a transparent electrode formed on said even surface of said semiconductor layer, wherein said transparent electrode has an even surface, and
a light lead-out layer formed on said even surface of said transparent electrode, said light lead-out layer being provided an embossment on a surface thereof.
6. The semiconductor light emitting device according to claim 5 , wherein said light lead-out layer is made of an organic material or an inorganic material.
7. The semiconductor light emitting device according to claim 5 , wherein said light lead-out layer includes fluorescent material.
8. A semiconductor light emitting device comprising:
a substrate;
a light emitting portion formed on one surface of said substrate;
a semiconductor layer formed on said light emitting portion, said semiconductor layer having an even surface; and
a reflector formed on said semiconductor layer; and
a light lead-out layer formed on another surface of said substrate opposite to said reflector, said lead-out layer being provided an embossment on a surface thereof.
9. The semiconductor light emitting device according to claim 8 , wherein said reflector also serves as an electrode for said light emitting portion.
10. A manufacturing method of a semiconductor light emitting device comprising:
forming a compound semiconductor having a light emitting portion;
forming a metal layer containing a dopant on a surface of said compound semiconductor;
diffusing said dopant into said compound semiconductor;
removing said metal layer from the surface of said compound semiconductor;
forming an embossment on the surface of said compound semiconductor; and
forming an electrode on the surface of said compound semiconductor.
11. The manufacturing method of a semiconductor light emitting device according to claim 10 , further comprising forming a contact metal layer between the surface of said compound semiconductor and said electrode.