Light emitting element

• US 8,674,384 B2
• Filed: 03/15/2011
• Issued: 03/18/2014
• 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
• Primary Examiner(s): Clark, S. V.
• Assistant Examiner(s): Miyoshi, Jesse Y
• Application Number:
  US13/048,046
• Publication Number:
  US 20120104431A1
• Time in Patent Office: 1,099 Days
• Field of Search: 257/79, 257/94, 257/95, 257/E33.043, 257/E33.067, 257/E33.074, 257/101, 257/102
• US Class Current: 257/95
• 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, wherein a first impurity concentration of the first layer is the same as a second impurity concentration of the surface processed layer;

a second layer of the first conductivity type provided between the surface processed layer and the first layer, the second layer having an impurity concentration higher than a third 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,

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

wherein the third impurity concentration of the current spreading layer is not less than 5×

10¹⁷ cm<sup>−

3</sup> and not more than 3×

10¹⁸ cm<sup>−

3</sup>, and the third impurity concentration of the current spreading layer is greater than a fourth impurity concentration of the cladding 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).

7. The element according to claim 1, wherein

a thickness of the current spreading layer is not more than 5 μ

m.

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, wherein a first impurity concentration of the first layer is the same as a second impurity concentration of the surface processed layer;

a second layer of the first conductivity type provided between the surface processed layer and the first 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,

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

wherein at least one dopant included in one of the surface processed layer and the second layer is not included in the other of the surface processed layer and the second layer, a third impurity concentration of the current spreading layer is not less than 5×

10¹⁷ cm³ and not more than 3×

10¹⁸ cm<sup>−

3</sup>, and the third impurity concentration of the current spreading layer is greater than a fourth impurity concentration of the cladding layer, and

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.

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 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.

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).

13. The element according to claim 8, wherein

a thickness of the current spreading layer is not more than 5 μ

m.