Light-emitting diode and manufacturing method therefor

1. An LED epitaxial structure, comprising:

a growth substrate;

an n-type gradient buffer layer over the growth substrate;

an n-type semiconductor layer over the n-type gradient buffer layer;

an active layer over the n-type semiconductor layer; and

a p-type semiconductor layer over the active layer;

wherein an n-type doping of the n-type gradient buffer layer has a Gaussian distribution, and a side of the n-type gradient buffer layer adjacent to the growth substrate is highly doped.

2. The LED epitaxial structure of claim 1 , wherein an n-type doping concentration of the n-type gradient buffer layer is more than 1×10 18 .

3. The method of claim 1 , wherein the n-type doping of the n-type gradient buffer layer has a Gaussian distribution, and a side of the n-type gradient buffer layer adjacent to the growth substrate is highly doped.

4. A method for LED epitaxial growth, comprising:

1) providing a growth substrate, on which a u-doped buffer layer is formed via a first epitaxial growth;

2) transforming the buffer layer into an n-type gradient buffer layer through ion implantation;

3) forming an n-type semiconductor layer via a second epitaxial growth on the n-type gradient buffer layer;

4) forming an active layer on the n-type semiconductor layer via epitaxial growth; and

5) forming a p-type semiconductor layer on the active layer via epitaxial growth.

5. A vertical LED chip structure, comprising:

a conductive substrate;

a light-emitting epitaxial layer on the conductive substrate including an n-type semiconductor layer, a p-type semiconductor layer and an active layer between the two;

an n-type gradient buffer layer formed on the n-type semiconductor layer; and

an n-electrode formed on the n-type gradient buffer layer;

wherein an n-type doping of the n-type gradient buffer layer has a Gaussian distribution, and a side of the n-type gradient buffer layer adjacent to the n-type semiconductor layer is highly doped.

6. The vertical LED chip structure as claimed in claim 5 , wherein an n-type doping concentration of the n-type gradient buffer layer is more than 1×10 18 and ranges from 1×10 18 to 1×10 20 .

7. The vertical LED chip structure of claim 5 , wherein

a doping concentration of the highly-doped side is 1×10 18 ˜5×10 18 .

8. The vertical LED chip structure of claim 5 , wherein a side of the n-type gradient buffer layer away from the n-type semiconductor layer is highly doped with a doping concentration of 5×10 18 ˜1×10 20 .

9. The vertical LED chip structure of claim 5 , wherein the n-type gradient buffer layer has a flat surface or a patterned concave-convex surface.

10. A method for making the vertical LED of claim 5 , comprising:

1) providing a growth substrate, on which a u-doped buffer layer is formed via a first epitaxial growth;

2) transforming the buffer layer into an n-type gradient buffer layer through ion implantation;

3) forming an n-type semiconductor layer, an active layer and a p-type semiconductor layer via a second epitaxial growth on the n-type gradient buffer layer to thereby form an LED epitaxial structure;

4) forming a metal reflecting layer on the p-type semiconductor layer;

5) bonding a conductive substrate with the epitaxial structure;

6) removing the growth substrate and exposing a surface of the n-type gradient buffer layer;

7) making an n-electrode on the exposed n-type gradient buffer layer; and making a p-electrode on a back of the conductive substrate; and 8)

forming a vertical LED chip by cutting.

11. The method of claim 10 , wherein the n-type doping concentration of the n-type gradient buffer layer is more than 1×10 18 and ranges from 1×10 18 to 1×10 20 .

12. The method of claim 10 , wherein the n-type doping of the n-type gradient buffer layer has a Gaussian distribution, and a side adjacent to the n-type semiconductor layer has a low doping.

13. The method of claim 10 , wherein in step 2), an n-type gradient buffer layer is formed by injecting Si ion in the buffer layer.