Light-emitting device

1. A light-emitting device comprising:

a semiconductor light-emitting stack;

a current injected portion formed on the semiconductor light-emitting stack;

an extension portion having a first branch radiating from the current injected portion and a second branch extending from the first branch;

an electrical contact structure between the second branch and the semiconductor light-emitting stack and comprising a first width; and

a current blocking structure located right beneath the electrical contact structure and comprising a second width larger than the first width.

2. A light-emitting device of claim 1 , wherein the current blocking structure has an area larger than that of the electrical contact structure.

3. A light-emitting device of claim 1 , wherein the current blocking structure has a pattern similar to that of the electrical contact structure.

4. A light-emitting device of claim 1 , wherein the second branch is electrically connected to the electrical contact structure, and the first branch is current-blocked with the semiconductor light-emitting stack.

5. A light-emitting device of claim 1 , wherein the current blocking structure comprises a metal forming a Schottky contact with the transparent conductive oxide layer.

6. A light-emitting device of claim 1 , wherein the electrical contact structure comprises a first length, the first length is greater than the first width.

7. A light-emitting device of claim 1 , wherein the electrical contact structure and the second branch substantially have the same shape.

8. A light-emitting device of claim 1 , wherein the current blocking structure and the second branch substantially have the same shape.

9. A light-emitting device of claim 1 , further comprising:

a substrate;

an adhesive layer; and

a reflective layer;

wherein the adhesive layer and the reflective layer are sandwiched by the semiconductor light-emitting stack and the substrate.

10. A light-emitting device of claim 1 , wherein the semiconductor light-emitting stack comprises a roughened surface.

11. A light-emitting device of claim 1 , further comprising a transparent conductive oxide layer under the semiconductor light-emitting stack.

12. A light-emitting device of claim 1 , wherein the electrical contact structure is not parallel to the first branch.

13. A light-emitting device of claim 1 , wherein the current blocking structure is not parallel to the first branch.

14. A light-emitting device of claim 1 , wherein the current blocking structure has an area larger than that of the second branch.

15. A light-emitting device of claim 1 , wherein the second branch comprises a third width, the second width is larger than the third width.