LED with current spreading layer and fabrication method

1. A light emitting diode (LED) comprising:

an n side layer and a p side layer formed with nitride semiconductors, respectively;

an active layer comprising a nitride semiconductor between the n side layer and the p side layer;

wherein:

the n side layer is successively laminated by an extrinsically-doped buffer layer and a compound multi-current spreading layer; the compound multi-current spreading layer is successively-laminated by a first current spreading layer, a second current spreading layer and a third current spreading layer;

the first current spreading layer and the third current spreading layer each are alternatively-laminated layers comprising a u-type nitride semiconductor layer and an n-type nitride semiconductor layer; the second current spreading layer is a distributed insulation layer formed on the n-type nitride semiconductor layer; and

the first current spreading layer is on the extrinsically-doped buffer layer, and the third current spreading layer is adjacent to the active layer;

wherein the third current spreading layer is configured for a two-dimensional spreading of current from distributed point current sources formed by the second current spreading layer; and

wherein the extrinsically-doped buffer layer is configured for directly coupling to an electrode metal layer.

2. The LED of claim 1 , wherein the compound multi-current spreading layer further comprises a Si-doped n-type nitride gradient semiconductor layer between the second current spreading layer and the third current spreading layer.

3. The LED of claim 2 , further comprising a conductive substrate, and a vertical light-emitting epitaxial structure including the p side layer, the active layer and the n side layer disposed over the conductive substrate.

4. The LED of claim 2 , wherein the distributed insulation layer comprises insulation portions separated with preset intervals.

5. The LED of claim 2 , wherein a film thickness of the compound multi-current spreading layer is about 1000 Å-100000 Å.

6. The LED of claim 2 , wherein a film thickness of the second current spreading layer is about 100 Å-5000 Å.

7. The LED of claim 2 , wherein a film thickness of the Si-doped n-type nitride gradient semiconductor layer is about 200 Å-5000 Å.

8. The LED of claim 2 , wherein the Si-doped n-type nitride gradient semiconductor layer is formed through second epitaxial growth and the Si-doping concentration gradually varies from 1×10 17 cm −3 to 5×10 19 cm −3 .

9. The LED of claim 8 , wherein, the Si-doped n-type nitride gradient semiconductor layer is formed through secondary epitaxial growth and the Si-doping concentration gradually varies from 5×10 17 cm −3 to 1×10 19 cm −3 .

10. The LED of claim 2 , wherein a film thickness of the first current spreading layer and the third current spreading layer is about 350 Å-45000 Å; a film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is more than 0.8 and the number of laminated cycles is 1-100.

11. The LED of claim 10 , wherein a film thickness of the first current spreading layer is about 10000 Å-40000 Å; a film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is 1.5:1 and the number of laminated cycles is 40.

12. The LED of claim 11 , wherein a film thickness of the third current spreading layer is about 4000 Å-18000 Å; a film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is 1:1 and a number of laminated cycles is 18.

13. The LED of claim 1 , wherein in the first current spreading layer and the third current spreading layer, the Si-doping concentration in the u-type nitride semiconductor layer is less than 5×10 17 cm −3 and the Si-doping concentration in the n-type nitride semiconductor layer is more than 1×10 18 cm −3 .

14. A system comprising one or more light emitting diodes (LEDs), wherein each LED comprises:

an n-side layer and a p-side layer formed with nitride semiconductors, respectively;

an active layer comprising a nitride semiconductor between the n-side layer and the p-side layer;

wherein:

the n-side layer is successively laminated by an extrinsically-doped buffer layer and a compound multi-current spreading layer; the compound multi-current spreading layer is successively-laminated by a first current spreading layer, a second current spreading layer and a third current spreading layer;

the first current spreading layer and the third current spreading layer each are alternatively-laminated layers comprising a u-type nitride semiconductor layer and an n-type nitride semiconductor layer; the second current spreading layer is a distributed insulation layer formed on the n-type nitride semiconductor layer; and

the first current spreading layer is on the extrinsically-doped buffer layer, and the third current spreading layer is adjacent to the active layer;

wherein the third current spreading layer is configured for a two-dimensional spreading of current from distributed point current sources formed by the second current spreading layer; and

wherein the extrinsically-doped buffer layer is configured for directly coupling to an electrode metal layer.

15. The system of claim 14 , wherein the compound multi-current spreading layer further comprises a Si-doped n-type nitride gradient semiconductor layer between the second current spreading layer and the third current spreading layer.

16. A fabrication method for a light emitting diode (LED), comprising:

providing a growth substrate and forming an n-side layer with a nitride semiconductor over the substrate;

forming an active layer with a nitride semiconductor over the n-side layer;

forming a p-side layer with a nitride semiconductor over the active layer to form an epitaxial structure;

wherein:

the n-side layer is successively laminated by an extrinsically-doped buffer layer and a compound multi-current spreading layer; the compound multi-current spreading layer is successively-laminated by a first current spreading layer, a second current spreading layer and a third current spreading layer;

the first current spreading layer and the third current spreading layer are alternatively-laminated layers comprising a u-type nitride semiconductor layer and an n-type nitride semiconductor layer; the second current spreading layer is a distributed insulation layer formed on the n-type nitride semiconductor layer; and

the first current spreading layer is on the extrinsically-doped buffer layer, and the third current spreading layer is adjacent to the active layer;

wherein the resulting LED comprises:

the n side layer and the p side layer formed with nitride semiconductors, respectively;

the active layer comprising a nitride semiconductor between the n side layer and the p side layer;

wherein:

the n side layer is successively laminated by an extrinsically-doped buffer layer and a compound multi-current spreading layer; the compound multi-current spreading layer is successively-laminated by the first current spreading layer, the second current spreading layer and the third current spreading layer;

the first current spreading layer and the third current spreading layer each are alternatively-laminated layers comprising a u-type nitride semiconductor layer and an n-type nitride semiconductor layer; the second current spreading layer is a distributed insulation layer formed on the n-type nitride semiconductor layer; and

the first current spreading layer is adjacent to the extrinsically-doped buffer layer, and the third current spreading layer is adjacent to the active layer;

wherein the third current spreading layer is configured for a two-dimensional spreading of current from distributed point current sources formed by the second current spreading layer; and

wherein the extrinsically-doped buffer layer is configured for directly coupling to an electrode metal layer.

17. The method of claim 16 , wherein said forming the n-side layer comprises:

forming an extrinsically-doped buffer layer, a first current spreading layer and a second current spreading layer on the growth substrate through epitaxial growth in successive, and forming a distributed insulation layer with parts isolated at preset interval on the second current spreading layer through ion implantation; and

forming a third current spreading layer on the second current spreading layer through second epitaxial growth.

18. The method of claim 17 , further comprising:

forming a Si-doped n-type nitride gradient semiconductor layer between the second current spreading layer and the third current spreading layer.

19. The method of claim 18 , further comprising:

providing a conductive substrate;

bonding the epitaxial structure with the conductive substrate;

removing the growth substrate; and

fabricating a p electrode and an n electrode to form a vertical LED.

20. The method of claim 19 , wherein:

in the first current spreading layer and the third current spreading layer, the Si-doping concentration in the u-type nitride semiconductor layer is less than 5×10 17 cm −3 and the Si-doping concentration in the n-type nitride semiconductor layer is more than 1×10 18 cm −3 ;

the film thickness of the compound multi-current spreading layer is 1000 Å-100000 Å;

the film thickness of the third current spreading layer is 4000 Å-18000 Å;

the film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is 1:1 and the number of laminated cycles is 18;

the film thickness of the first current spreading layer and the third current spreading layer is 350 Å-45000 Årespectively;

the film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is more than 0.8 and the number of laminated cycles is 1-100; and

the film thickness of the first current spreading layer is 10000 Å-40000 Å; the film thickness ratio between the u-type nitride semiconductor layer and the n-type nitride semiconductor layer is 1.5:1 and the number of laminated cycles is 40.