Semiconductor light emitting element

• US 7,763,907 B2
• Filed: 09/05/2007
• Issued: 07/27/2010
• Est. Priority Date: 01/25/2007
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nunoue, Shinya, Tachibana, Koichi, Nago, Hajime, Saito, Shinji, Hatakoshi, Genichi
• Primary Examiner(s): Landau; Matthew C
• Assistant Examiner(s): STANISZEWSKI, AARON J
• Application Number:
  US11/850,404
• Publication Number:
  US 20080179623A1
• Time in Patent Office: 1,056 Days
• Field of Search: 257 9- 39, 257 79-103, 257E33001-E33077, 257/623, 257/626, 257/627, 257/628, 257/739, 257/745, 257E2109-E21134, 372/45.01, 372/44.011, 372/46.01, 438/44, 438/42, 438/32, 438604-609
• US Class Current: 257/99
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A semiconductor light emitting element includes: an {0001} n-type semiconductor substrate formed of a III-V semiconductor, which is in a range of 0° to 45° in inclination angle into a <1-100> direction, and which is in a range of 0° to 10° in inclination angle into a <11-20> direction; an n-type layer formed of a III-V semiconductor on the n-type semiconductor substrate; an n-type guide layer formed of a III-V semiconductor above the n-type layer; an active layer formed of a III-V semiconductor above the n-type guide layer; a p-type first guide layer formed of a III-V semiconductor above the active layer; a p-type contact layer formed of a III-V semiconductor above the p-type first guide layer; and an concavo-convex layer formed of a III-V semiconductor between the p-type first guide layer and the p-type contact layer. The concavo-convex layer has concave portions and convex portions which are alternately and regularly arranged at a top face thereof, and has lower p-type impurity concentration than that of the p-type contact layer.

Claims

1. A semiconductor light emitting element comprising:

an {0001} n-type semiconductor substrate formed of a III-V semiconductor, which is in a range of 0°

to 45°

in inclination angle into a <

1-100>

direction, and which is in a range of 0°

to 10°

in inclination angle into a <

11-20>

direction except the inclination angle of 0°

in both the <

1-100>

direction and the <

11-20>

direction;

an n-type layer formed of a III-V semiconductor on the n-type semiconductor substrate;

an n-type guide layer formed of a III-V semiconductor above the n-type layer;

an active layer formed of a III-V semiconductor above the n-type guide layer;

a p-type first guide layer formed of a III-V semiconductor above the active layer;

a p-type contact layer formed of a III-V semiconductor above the p-type first guide layer;

a concavo-convex layer formed of In_xGa_1-x-yAl_yN (0<

x<

1, 0<

y<

1) between the p-type first guide layer and the p-type contact layer, the concavo-convex layer having concave portions and convex portions which are alternately and regularly arranged at a top face thereof and having lower p-type impurity concentration than that of the p-type contact layer, a composition y of Al in the concavo-convex layer being in a range of 0.001% to 6%, and the height difference from a top of a convexity to a bottom of its neighboring concavity in the concavo-convex layer is in a range of 5 nm to 200 nm, wherein concave portions and convex portions are formed partly as a result of substrate orientation and without a dedicated etching step;

a first electrode formed on the p-type contact layer and extending across the concave portions and convex portions,

the p-type contact layer having concave portions and convex portions corresponding to the concave portions and the convex portions of the concavo-convex layer respectively, and

the p-type contact layer and the concavo-convex layer being formed by crystal growth respectively.

2. The light emitting element according to claim 1, further comprising:

an electron overflow prevention layer formed of a III-V semiconductor between the p-type first guide layer and the concavo-convex layer; and

a p-type second guide layer formed of a III-V semiconductor between the electron overflow prevention layer and the concavo-convex layer.

3. The light emitting element according to claim 1, further comprising:

an electron overflow prevention layer formed of a III-V semiconductor between the p-type first guide layer and the concavo-convex layer; and

a p-type second guide layer formed of a III-V semiconductor between the concavo-convex layer and the p-type contact layer.

4. The light emitting element according to claim 1, further comprising:

an electron overflow prevention layer formed of a III-V semiconductor between the active layer and the p-type first guide layer.

5. The light emitting element according to claim 1, further comprising:

a second electrode provided on one side of the n-type semiconductor substrate opposite from the n-type layer.

6. The light emitting element according to claim 1, further comprising:

a second electrode provided on the n-type layer in a region formed by removing a part of a stacked structure extending from the p-type contact layer to the n-type layer.

7. The light emitting element according to claim 1, further comprising:

an n-type cladding layer formed of a III-V semiconductor and being provided between the n-type layer and the n-type guide layer;

a p-type cladding layer formed of a III-V semiconductor and being provided between the p-type first guide layer and the concavo-convex layer, and having a convex part; and

an electron overflow prevention layer formed of a III-V semiconductor and being provided either between the active layer and the p-type first guide layer or between the p-type first guide layer and the p-type cladding layer,

wherein the concavo-convex layer and the p-type contact layer are provided on a top face of the convex part of the p-type cladding layer.

8. The light emitting element according to claim 7, wherein

the electron overflow prevention layer is provided between the p-type first guide layer and the p-type cladding layer, and

the semiconductor light emitting element further comprises a p-type second guide layer formed of a III-V semiconductor between the electron overflow prevention layer and the p-type cladding layer.

9. The light emitting element according to claim 7, further comprising:

a current block layer provided so as to cover side faces of the convex part of the p-type cladding layer, the concavo-convex layer, and the p-type contact layer, and cover regions of the p-type cladding layer other than the convex part; and

a second electrode on one side of the n-type semiconductor substrate opposite from the n-type layer.

10. The light emitting element according to claim 1, wherein any one of the III-V semiconductors is a nitride semiconductor.

11. The light emitting element according to claim 1, wherein the concavo-convex layer has a facet of one of a {1-101} plane, a {1-102} plane, a {11-21} plane and a {11-22} plane, or a plane obtained by combining them.

12. The light emitting element according to claim 1, wherein the distance between a convexity and its neighboring convexity or the distance between a concavity and its neighboring concavity in the concavo-convex layer is in a range of 5 nm to 100 nm.

13. The light emitting element according to claim 1, further comprising:

a p-type cladding layer formed of a III-V semiconductor, provided between the p-type first guide layer and the concavo-convex layer, and patterned into a ridge structure having side faces.

14. The light emitting element according to claim 13, further comprising:

a current block layer disposed on the side faces of the ridge structure in contact with the p-type cladding layer and the concavo-convex layer.

15. The light emitting element according to claim 14, wherein the first electrode is disposed to overlap the p-type contact layer at the top of the ridge structure and the current block layer on the side faces of the ridge structure.

16. A semiconductor light emitting element comprising:

an {0001} n-type semiconductor substrate formed of a III-V semiconductor, which is in a range of 0°

to 45°

in inclination angle into a <

1-100>

direction, and which is in a range of 0°

to 10°

in inclination angle into a <

11-20>

direction except the inclination angle of 02°

in both the <

1-100>

direction and the <

11-20>

direction;

an n-type layer formed of a III-V semiconductor on the n-type semiconductor substrate;

an n-type guide layer formed of a III-V semiconductor above the n-type layer;

an active layer formed of a III-V semiconductor above the n-type guide layer;

a p-type first guide layer formed of a III-V semiconductor above the active layer;

a p-type contact layer formed of a III-V semiconductor above the p-type first guide layer;

a concavo-convex layer formed of a III-V semiconductor between the p-type first guide layer and the p-type contact layer, the concavo-convex layer having concave portions and convex portions which are alternately and regularly arranged at a top face thereof and having lower p-type impurity concentration than that of the p-type contact layer, wherein concave portions and convex portions are formed partly as a result of substrate orientation and without a dedicated etching step;

an electrode formed on the p-type contact layer and extending across the concave portions and convex portions,

the p-type contact layer having concave portions and convex portions corresponding to the concave portions and the convex portions of the concavo-convex layer respectively, and

the p-type contact layer and the concavo-convex layer being formed by crystal growth respectively.