Light-emitting diode having a roughened surface

1. A light-emitting diode, comprising:

a substrate, the substrate comprising an upper surface, a bottom surface opposite to the upper surface, and a side surface;

a first type semiconductor layer on the upper surface, wherein the first type semiconductor layer comprises a first portion and a second portion, and the second portion comprises an edge surrounding the first portion;

a light-emitting layer on the first portion; and

a second type semiconductor layer on the light-emitting layer,

wherein the second portion comprises a first surface and a second surface, and a first distance is between the first surface and the upper surface, and a second distance is between the second surface and the upper surface and is smaller than the first distance,

wherein the first surface is rougher than the second surface, and the second surface is located at the edge.

2. A light-emitting diode according to claim 1 , wherein the substrate comprises a transparent substrate.

3. A light-emitting diode according to claim 1 , wherein the second portion further comprises a third surface, wherein a distance between the third surface and the upper surface is equal to the second distance, and the third surface comprises a third average roughness (Ra) in a range of 10 nm to 100 nm.

4. A light-emitting diode according to claim 3 , further comprises a first electrical pad on the third surface.

5. A light-emitting diode according to claim 1 , wherein the width of the second surface is between 5 μm and 15 μm.

6. A light-emitting diode according to claim 1 , wherein the first distance is 2000 Å to 10000 Å larger than the second distance.

7. A light-emitting diode according to claim 1 , wherein the first surface comprises a first average roughness (Ra) larger than 100 nm, and/or the second surface comprises a second average roughness (Ra) in a range of 10 nm to 100 nm.

8. A light-emitting diode according to claim 1 , further comprising a reflective layer on the bottom surface.

9. A light-emitting diode according to claim 7 , wherein the second type semiconductor layer comprises a fifth surface and a fourth surface, and the fifth surface is rougher than the fourth surface.

10. A light-emitting diode according to claim 9 , wherein the fourth surface comprises a fourth average roughness (Ra) in a range of 10 nm to 100 nm.

11. A light-emitting diode according to claim 10 , wherein the difference between the fourth average roughness (Ra) and the second average roughness (Ra) is smaller than 50 nm.

12. A light-emitting diode according to claim 1 , further comprising a damaged region on the side surface and distant from upper surface and bottom surface.

13. A light-emitting diode, comprising:

a first type semiconductor layer, wherein the first type semiconductor layer comprises a first portion and a second portion, and the second portion comprises a first surface and a second surface;

a light-emitting layer on the first portion; and

a second type semiconductor layer on the light-emitting layer, wherein the second type semiconductor layer comprises a fifth surface,

wherein the first surface and the fifth surface are rougher than the second surface, and the second surface surrounds the first portion.