Light-emitting diode device and method for manufacturing the same
A light-emitting diode (LED) device includes a substrate, an epitaxial layered structure disposed on the substrate, a current-spreading layer disposed on the epitaxial layered structure, a current-blocking unit disposed on the current-spreading layer, and a distributed Bragg reflector. The epitaxial layered structure, the current-spreading layer and the current-blocking unit are covered by the distributed Bragg reflector. One of the current-spreading layer, the current-blocking unit, and a combination thereof has a patterned rough structure. A method for manufacturing the LED device is also disclosed.
1. A light-emitting diode device, comprising:
a substrate;
an epitaxial layered structure which includes a first-type semiconductor layer, an active layer, and a second-type semiconductor layer sequentially formed on said substrate in such order, and which is formed with an indentation extending through said second-type semiconductor layer and said active layer and terminating at said first-type semiconductor layer to expose a portion of said first-type semiconductor layer;
a first current-blocking layer formed on said epitaxial layered structure opposite to said substrate;
a current-spreading layer which is disposed on said epitaxial layered structure opposite to said substrate, which is disposed over said first current-blocking layer, and which is connected to said epitaxial layered structure;
a second current-blocking layer which is formed on said current-spreading layer opposite to said epitaxial layered structure; and
a distributed Bragg reflector which covers said epitaxial layered structure, said current-spreading layer, and said second current-blocking layer.
2. The light-emitting diode device according to claim 1 , wherein a width of said second current-blocking layer is larger than a width of said first current-blocking layer.
3. The light-emitting diode device according to claim 1 , wherein an area of said second current-blocking layer is larger than an area of said first current-blocking layer.
4. The light-emitting diode device according to claim 3 , wherein said first current-blocking layer is made of a material having a relatively low refractive index, and said second current-blocking layer is made of a material having a relatively high refractive index.
5. The light-emitting diode device according to claim 1 , wherein said distributed Bragg reflector has a thickness of not less than 3 μm.
6. The light-emitting diode according to claim 1 , wherein said second current-blocking layer is formed with an opening, and said light-emitting diode further includes a first electrode unit that contains a first electrode disposed on said current-spreading layer and extending into said opening of said second current-blocking layer.
7. The light-emitting diode according to claim 1 , wherein said distributed Bragg reflector is formed with a first through hole, and said light-emitting diode further includes a first electrode unit that contains a second electrode being formed in said first through hole and being electrically connected to said current-spreading layer.
8. The light-emitting diode device according to claim 6 , wherein said first current-blocking layer is under said first electrode unit, and said second current-blocking layer surrounds said first electrode of said first electrode unit.
9. The light-emitting diode according to claim 1 , wherein one of said current-spreading layer, said first current-blocking layer, said second current-blocking layer and a combination thereof has an upper surface with a patterned rough structure.
10. The light-emitting diode according to claim 9 , wherein said second current-blocking layer has said upper surface with said patterned rough structure, each of said first current-blocking layer and said current-spreading layer has a smooth upper surface.
11. The light-emitting diode according to claim 6 , wherein said first current-blocking layer is under said first electrode unit.
12. The light-emitting diode according to claim 6 , wherein said distributed Bragg reflector is formed with a first through hole, and said first electrode unit further contains a second electrode disposed on said distributed Bragg reflector and electrically connected to said first electrode through said first through hole.
13. The light-emitting diode according to claim 12 , wherein said distributed Bragg reflector is formed with a second through hole, and said light-emitting diode further includes a second electrode unit disposed on said distributed Bragg reflector and electrically connected to said first-type semiconductor layer through said second through hole.
14. The light-emitting diode device according to claim 10 , wherein said patterned rough structure has a plurality of protrusions that protrude in a direction away from said epitaxial layered structure.
15. The light-emitting diode device according to claim 14 , wherein each of said protrusions is one of a hemispherical protrusion, a conical protrusion, and a frustoconical protrusion.
16. The light-emitting diode device according to claim 15 , wherein a projection of each of said protrusions on said epitaxial layered structure has a diameter of not greater than 50 μm.
17. The light-emitting diode device according to claim 14 , wherein each of said protrusions has a height of not less than 100 nm.
18. The light-emitting diode device according to claim 14 , wherein a distance between two adjacent ones of said protrusions is not greater than 20 μm.
19. The light-emitting diode device according to claim 14 , wherein said current-spreading layer is transparent.