LIGHT EMITTING ELEMENT

• US 20120104431A1
• Filed: 03/15/2011
• Published: 05/03/2012
• Est. Priority Date: 11/02/2010
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kataoka, Takashi, Nishikawa, Yukie, Yamasaki, Hironori
• Granted Patent: US 8,674,384 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

According to one embodiment, a light emitting element includes a light emitting layer, a cladding layer, a current spreading layer, a second layer, and an electrode. The light emitting layer is capable of emitting emission light. The current spreading layer includes a surface processed layer and a first layer. The surface processed layer has a surface including convex portions and bottom portions provided adjacent to the convex portions. The first layer is provided between the surface processed layer and the cladding layer. The second layer is provided between the surface processed layer and the cladding layer and includes a region having an impurity concentration higher than an impurity concentration of the current spreading layer. The electrode is provided in a region of the surface of the surface processed layer where the convex portions and the bottom portions are not provided.

Claims

1. A light emitting element, comprising:

a light emitting layer capable of emitting emission light;

a cladding layer of a first conductivity type;

a current spreading layer of the first conductivity type including a surface processed layer and a first layer, the surface processed layer having a surface including convex portions and bottom portions provided adjacent to the convex portions, the first layer being provided between the surface processed layer and the cladding layer;

a second layer of the first conductivity type provided between the surface processed layer and the cladding layer and including a region having an impurity concentration higher than an impurity concentration of the current spreading layer; and

an electrode provided in a region of the surface of the surface processed layer where the convex portions and the bottom portions are not provided,

the cladding layer, the current spreading layer, and the second layer being provided on one surface side of the light emitting layer.

2. The element according to claim 1, wherein the convex portions are island-like or mesh-like.

3. The element according to claim 2, wherein the convex portions are configured to have an average pitch not more than a wavelength of the emission light.

4. The element according to claim 1, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

the second layer has a peak impurity concentration not less than 5×

10¹⁸ cm<sup>−

3</sup> and a thickness not more than 100 nm.

5. The element according to claim 1, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

the second layer is formed as a delta-doped layer having a sheet concentration in a range between 5×

10¹² cm<sup>−

2</sup> and 1.5×

10¹³ cm<sup>−

2</sup>, inclusive.

6. The element according to claim 1, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

a dopant included in the current spreading layer and a dopant included in the second layer are different from each other in at least one element.

7. The element according to claim 1, wherein

the second layer has a first film on the surface processed layer side and a second film on the cladding layer side, and

the first layer includes a region between the first film and the second film.

8. A light emitting element, comprising:

a light emitting layer capable of emitting emission light;

a cladding layer of a first conductivity type;

a current spreading layer of the first conductivity type including a surface processed layer and a first layer, the surface processed layer having a surface including convex portions and bottom portions provided adjacent to the convex portions, the first layer being provided between the surface processed layer and the cladding layer;

a second layer of the first conductivity type provided between the surface processed layer and the cladding layer and including one of a region having an impurity concentration higher than an impurity concentration of the current spreading layer and a region having a dopant different from a dopant of the current spreading layer; and

an electrode provided in a region of the surface of the surface processed layer where the convex portions and the bottom portions are not provided,

the cladding layer, the current spreading layer, and the second layer being provided on one surface side of the light emitting layer.

9. The element according to claim 8, wherein the convex portions are island-like or mesh-like.

10. The element according to claim 9, wherein the convex portions are configured to have an average pitch not more than a wavelength of the emission light.

11. The element according to claim 8, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

the second layer has a peak impurity concentration not less than 5×

10¹⁸ cm<sup>−

3</sup> and a thickness not more than 100 nm.

12. The element according to claim 8, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

the second layer is formed as a delta-doped layer having a sheet concentration in a range between 5×

10¹² cm<sup>−

2</sup> and 1.5×

10¹³ cm<sup>−

2</sup>, inclusive.

13. The element according to claim 8, wherein

each of the light emitting layer, the cladding layer, the current spreading layer, and the second layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1), and

a dopant included in the current spreading layer and a dopant included in the second layer are different from each other in at least one element.

14. The element according to claim 8, wherein

the second layer has a first film on the surface processed layer side and a second film on the cladding layer side, and

the first layer includes a region between the first film and the second film.

15. A light emitting element, comprising:

a light emitting layer capable of emitting emission light;

a cladding layer of a first conductivity type;

a current spreading layer of the first conductivity type including a surface processed layer and a first layer, the surface processed layer having a surface including convex portions and bottom portions provided adjacent to the convex portions, the first layer being provided between the surface processed layer and the cladding layer;

a second layer of the first conductivity type provided between the surface processed layer and the cladding layer, including a constituent element different from a constituent element of the current spreading layer; and

an electrode provided in a region of the surface of the surface processed layer where the convex portions and the bottom portions are not provided,

the cladding layer, the current spreading layer, and the second layer being provided on one surface side of the light emitting layer.

16. The element according to claim 15, wherein the convex portions are island-like or mesh-like.

17. The element according to claim 16, wherein the convex portions are configured to have an average pitch not more than a wavelength of the emission light.

18. The element according to claim 15, wherein

each of the light emitting layer and the cladding layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1),

the current spreading layer is made of In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1),and

the second layer is made of one of Al_xGa_1-xAs (0≦

x≦

1), GaAs, GaP, and In_x(Ga_1-yAl_y)_1-xP (0≦

x≦

1 and 0≦

y≦

1).

19. The element according to claim 15, wherein

the second layer has a first film on the surface processed layer side and a second film on the cladding layer side, and

the first layer includes a region between the first film and the second film.