Nitride semiconductor device

• US 20060131604A1
• Filed: 02/07/2006
• Published: 06/22/2006
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Kozaki, Tokuya
• Granted Patent: US 7,646,009 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18369 based on dielectric materials
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/305 characterised by the doping materials used in the laser structure
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/3086 doping of the active layer
• CPC Class Codes: H01S 5/3407 characterised by special barrier layers
• CPC Class Codes: H01S 5/3415 containing details related to carrier capture times into wells or barriers
• CPC Class Codes: H01S 5/343 in AIIIBV compounds, e.g. AlGaAs-laser , InP-based laser
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

In the nitride semiconductor device of the present invention, an active layer 12 is sandwiched between a p-type nitride semiconductor layer 11 and an n-type nitride semiconductor layer 13. The active layer 12 has, at least, a barrier layer 2a having an n-type impurity; a well layer 1a made of a nitride semiconductor that includes In; and a barrier layer 2c that has a p-type impurity, or that has been grown without being doped. An appropriate injection of carriers into the active layer 12 becomes possible by arranging the barrier layer 2c nearest to the p-type layer side.

Claims

1. A nitride semiconductor device having a structure wherein an active layer of a quantum well structure, which has a well layer made of a nitride semiconductor that includes In and a barrier layer made of a nitride semiconductor, is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer,

wherein said active layer has 2 or more well layers, a first barrier layer arranged in a position nearest to said p-type nitride semiconductor layer, a second barrier layer that is different from the first barrier layer and a third barrier layer intervened between the well layers and sandwiched by said first barrier layer and said second barrier layer;

the film thickness of said third barrier layer being smaller than the film thickness of said first barrier layer and said second barrier layer;

the film thickness of said first barrier layer being approximately the same as that of said second barrier layer.

2. The nitride semiconductor device according to claim 1, wherein at least one well layer within said active layer has a film thickness of not less than 40 Å

.

3. The nitride semiconductor device according to claim 1, wherein said first barrier layer includes a p-type impurity.

4. The nitride semiconductor device according to claim 1, wherein said first barrier layer includes a p-type impurity in the range of no less than 5×

10¹⁶/cm<sup>−

3</sup> and no more than 1×

10¹⁹/cm<sup>−

3</sup>.

5. The nitride semiconductor device according to claim 1, wherein said first barrier layer is p-type or i-type.

6. The nitride semiconductor device according to claim 1, wherein said first barrier layer has been grown without being doped with an impurity and includes a p-type impurity through diffusion from said p-type nitride semiconductor layer.

7. The nitride semiconductor device according to claim 1, wherein said n-type nitride semiconductor layer, said active layer and said p-type nitride semiconductor layer are layered in sequence.

8. The nitride semiconductor device according to claim 1, wherein said device has a first p-type nitride semiconductor layer adjoining the active layer in said p-type nitride semiconductor layer, and said first p-type nitride semiconductor layer is made of a nitride semiconductor that includes Al.

9. The nitride semiconductor device according to claim 8, wherein said first p-type nitride semiconductor layer is provided so as to contact a barrier layer nearest to said p-type nitride semiconductor layer and has been grown being doped with a p-type impurity of which concentration is higher than that of said barrier layer in said active layer.

10. The nitride semiconductor device according to claim 1, wherein the number of well layers in said active layer is from 1 to 3.

11. The nitride semiconductor device according to claim 1, wherein said p-type nitride semiconductor layer includes a p-side optical guide layer and a p-side clad layer formed sequentially on said active layer;

and said p-type nitride semiconductor layer is partially cut away to the depth that a part of said p-side optical guide layer is removed to form a ridge stripe structure.

12. A nitride semiconductor device having a structure wherein an active layer of a quantum well structure, which has a well layer made of a nitride semiconductor that includes In and a barrier layer made of a nitride semiconductor, is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer,

wherein said active layer has 2 or more well layers, a first barrier layer arranged in a position nearest to said p-type nitride semiconductor layer, a second barrier layer that is different from the first barrier layer and a third barrier layer intervened between the well layers and sandwiched by said first barrier layer and said second barrier layer;

the n-type impurity concentration of said first barrier layer being not greater than 1×

10¹⁷/cm³ and the n-type concentration of said second barrier layer is not less than 5×

10¹⁷/cm³;

the film thickness of said third barrier layer being smaller than the film thickness of said first barrier layer and said second barrier layer;

the film thickness of said first barrier layer being approximately the same as that of said second barrier layer.

13. The nitride semiconductor device according to claim 12, wherein at least one well layer within said active layer has a film thickness of not less than 40 Å

.

14. The nitride semiconductor device according to claim 12, wherein said first barrier layer includes a p-type impurity.

15. The nitride semiconductor device according to claim 12, wherein said first barrier layer includes a p-type impurity in the range of no less than 5×

10¹⁶/cm<sup>−

3</sup> and no more than 1×

10¹⁹/cm<sup>−

3</sup>.

16. The nitride semiconductor device according to claim 12, wherein said first barrier layer is p-type or i-type.

17. The nitride semiconductor device according to claim 12, wherein said first barrier layer has been grown without being doped with an impurity and includes a p-type impurity through diffusion from said p-type nitride semiconductor layer.

18. The nitride semiconductor device according to claim 12, wherein said n-type nitride semiconductor layer, said active layer and said p-type nitride semiconductor layer are layered in sequence.

19. The nitride semiconductor device according to claim 12, wherein said device has a first p-type nitride semiconductor layer adjoining the active layer in said p-type nitride semiconductor layer, and said first p-type nitride semiconductor layer is made of a nitride semiconductor that includes Al.

20. The nitride semiconductor device according to claim 19, wherein said first p-type nitride semiconductor layer is provided so as to contact a barrier layer nearest to said p-type nitride semiconductor layer and has been grown being doped with a p-type impurity of which concentration is higher than that of said barrier layer in said active layer.

21. The nitride semiconductor device according to claim 12, wherein the number of well layers in said active layer is from 1 to 3.

22. The nitride semiconductor device according to claim 12, wherein said p-type nitride semiconductor layer includes a p-side optical guide layer and a p-side clad layer formed sequentially on said active layer;

and said p-type nitride semiconductor layer is partially cut away to the depth that a part of said p-side optical guide layer is removed to form a ridge stripe structure.