Light-emitting element with porous light-emitting layers

• US 7,271,417 B2
• Filed: 05/24/2005
• Issued: 09/18/2007
• Est. Priority Date: 10/20/2004
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Genesis Photonics Inc.
• Inventors: Chen, Cheng Chuan
• Primary Examiner(s): Louie; Wai-Sing
• Assistant Examiner(s): ARMAND, MARC ANTHONY
• Application Number:
  US11/135,639
• Publication Number:
  US 20060081832A1
• Time in Patent Office: 847 Days
• Field of Search: 257/79, 257/86, 257/94, 257/103, 438/22
• US Class Current: 257/79
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/18 within the light emitting region
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

The invention relates to a light-emitting element with porous light-emitting layers. The light-emitting element comprises: a substrate, a first conductive cladding layer, a second conductive cladding layer and at least one porous light-emitting layer. The porous light-emitting layer is formed between the first conductive cladding layer and the second conductive cladding layer, and has an upper barrier layer, a lower barrier layer and a carrier trap layer. The carrier trap layer positioned between the upper barrier layer and the lower barrier layer has a plurality of chevron structures for defining a plurality of valley shaped structures, and is an indium-containing nitride structure, the energy band gap of which is less than those of the upper barrier layer and the lower barrier layer. By utilizing the light-emitting element of the invention, the driving voltage of the element can be decreased significantly; thereby a preferred crystalline structure can be obtained so that the anti-static electricity ability and element reliability could be improved. Moreover, a plurality of porous light-emitting layers with different wavelengths may be grown on the light-emitting element of the invention, so as to elevate the performance of the light-emitting element effectively, and also to achieve a light-mixing element of a single chip, meanwhile so as to obtain the properties of high light-emitting benefit, high reliability, high light-mixing modularity and low cost and the like.

Claims

1. A light-emitting element with porous light-emitting layers, comprising:

a substrate;

a first conductive cladding layer;

a second conductive cladding layer; and

at least one porous light-emitting layer formed between the first conductive cladding layer and the second conductive cladding layer, the porous light-emitting layer having an upper barrier layer, a lower barrier layer and a carrier trap layer, the carrier trap layer positioned between the upper barrier layer and the lower barrier layer, the carrier trap layer having a plurality of chevron structures for defining a plurality of valley shaped structures, the carrier trap layer being an indium-containing nitride structure, the energy band gap of the carrier trap layer being less than that of the upper barrier layer and the lower barrier layer.

2. The light-emitting element according to claim 1, wherein the carrier trap layer is an aluminum indium gallium nitride structure that may be represented as Al_(1-x-y)In_yGa_xN, in which, x is no less than zero;

y is more than zero; and

(1-x-y) is no less than zero.

3. The light-emitting element according to claim 1, wherein the lower barrier layer and the upper barrier layer are both of aluminum indium gallium nitride structure that may be represented as Al_(1-x-y)In_yGa_xN, in which, x is more than zero;

y is no less than zero; and

(1-x-y) is no less than zero.

4. The light-emitting element according to claim 1, wherein the porous light-emitting layer is doped with a predetermined concentration of impurity, the content of which is between zero and 5×

10¹⁷/cm³.

5. The light-emitting element according to claim 1, wherein the distance between the bottom of each of the valley-shaped structures and the lower barrier layer is in the range of no less than zero to no more than 20×

10<sup>−

10</sup> meters, and the radial length of each of the valley-shaped structures is between 5×

10<sup>−

9</sup> and 1000×

10<sup>−

9</sup> meters.

6. The light-emitting element according to claim 5, wherein the density of the porous light-emitting layer is between 5% and 75%, which is the ratio of the sum of the radial length of all valley shaped structures to the radial length of the porous light-emitting layer.

7. A light-emitting element with porous light-emitting layers, including:

a substrate;

an N-type conductive cladding layer;

a P-type conductive cladding layer; and

at least one porous light-emitting layer with a first wavelength and at least one light-emitting layer with a second wavelength, formed between the N-type conductive cladding layer and the P-type conductive cladding layer, the porous light-emitting layer with the first wavelength being adjacent to the P-type conductive cladding layer, the first wavelength being different from the second wavelength, the porous light-emitting layer with the first wavelength having an upper barrier layer, a lower barrier layer and a carrier trap layer;

the carrier trap layer positioned between the upper barrier layer and the lower barrier layer, and the carrier trap layer having a plurality of chevron structures for defining a plurality of valley shaped structures;

the carrier trap layer being an indium-containing nitride structure, the energy band gap of the carrier trap layer being less than that of the upper barrier layer and the lower barrier layer.

8. The light-emitting element according to claim 7, which further includes a plurality of porous light-emitting layers formed between the N-type conductive cladding layer and the P-type conductive cladding layer, wherein the porous light-emitting layers have a plurality of light-emitting wavelengths, which are different from the first wavelength and the second wavelength.

9. The light-emitting element according to claim 7, wherein the carrier trap layer is an aluminum indium gallium nitride structure that may be represented as Al_(1-x-y)In_yGa_xN, in which, x is no less than zero;

y is more than zero; and

(1-x-y) is no less than zero.

10. The light-emitting element according to claim 7, wherein the lower barrier layer and the upper barrier layer are both an aluminum indium gallium nitride structure that may be represented as Al_(1-x-y)In_yGa_xN, in which, x is more than zero;

y is no less than zero; and

(1-x-y) is no less than zero.

11. The light-emitting element according to claim 7, wherein the porous light-emitting layers are doped with a predetermined concentration of impurity, the content of which is between 0 and 5×

10¹⁷/cm³.

12. The light-emitting element according to claim 7, wherein the distance between the bottom of each of the valley shaped structures and the lower barrier layer is in the range of no less than zero to no more than 20×

10<sup>−

9</sup> meters, and the radial length of each of the valley shaped structures is between 5×

10<sup>−

9</sup> and 1000×

10<sup>−

9</sup> meters.

13. The light-emitting element according to claim 12, wherein the density of the porous light-emitting layers is between 5% and 75%, which is the ratio of the sum of the radial length of all valley shaped structures to the radial length of the porous light-emitting layer.

14. The light-emitting element according to claim 13, wherein the light-emitting layer with the second wavelength is a porous light-emitting layer with the second wavelength.

15. The light-emitting element according to claim 14, wherein the porous light-emitting layer with the first wavelength has a first density, and the porous light-emitting layer with the second wavelength has a second density, the first density is larger than the second density.

16. The light-emitting element according to claim 14, wherein the first wavelength is smaller than the second wavelength.