Nitride semiconductor device

• US 9,444,011 B2
• Filed: 08/25/2015
• Issued: 09/13/2016
• Est. Priority Date: 07/07/2000
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Kozaki, Tokuya
• Primary Examiner(s): Nguyen, Thinh T
• Application Number:
  US14/834,470
• Publication Number:
  US 20150364649A1
• Time in Patent Office: 385 Days
• Field of Search: 257/13, 257/14, 257/94, 257/96, 257/97, 257/E33.002, 438/22, 438/46, 438/47
• US Class Current: 1/1
• 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 L (L≧

2) barrier layers so that the barrier layer arranged in a position nearest to said n-type nitride semiconductor layer is denoted as barrier layer B₁ and the i-th barrier layer (i=1, 2, 3, . . . L) counted from the barrier layer B₁ toward said p-type nitride semiconductor layer is denoted as barrier layer B_i;

wherein a barrier layer B_L (i=L)is formed between the well layer and a first p-type nitride semiconductor layer formed in said p-type nitride semiconductor layer, said first p-type nitride semiconductor layer being made of a nitride semiconductor including Al and having a larger band gap energy than said active layer,

wherein the barrier layer B_L is thicker than the barrier layer B_i (i≠

L), and

wherein a plurality of the barrier layers including the barrier layer B₁ and located on the n-type nitride semiconductor layer side are doped with an n-type impurity, and a plurality of the barrier layers including the barrier layer B_L and located on the p-type nitride semiconductor layer side are undoped with an n-type impurity.

2. The nitride semiconductor device according to claim 1, wherein the barrier layers B_i from i=1 to i=n (1<

n<

L) include an n-type impurity.

3. The nitride semiconductor device according to claim 1, wherein a concentration of the n-type impurity in the well layer is not more than a concentration of the n-type impurity in the barrier layer.

4. The nitride semiconductor device according to claim 1, wherein the well layer has a thickness of not less than 40 Å

.

5. The nitride semiconductor device according to claim 1, wherein at least one of the barrier layers is a stack of two or more layers of different compositions and/or impurity concentrations.

6. The nitride semiconductor device according to claim 5, wherein said stack of two or more layers includes Al_aGa₁₋

aN (0<

a≦

1) and In_bGa<sub>1−

b</sub>N (0≦

b<

1).

7. The nitride semiconductor device according to claim 1, wherein the barrier layer B_L adjoins to said first p-type nitride semiconductor layer.

8. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor device has a laser structure where said active layer is sandwiched by a p-side cladding layer made of a nitride semiconductor including Al and formed in said p-type nitride semiconductor layer and an n-side cladding layer made of a nitride semiconductor including Al and formed in said n-type nitride semiconductor layer.

9. The nitride semiconductor device according to claim 8, wherein said p-type nitride semiconductor layer includes a guide layer, and said first p-type nitride semiconductor layer is formed between said guide layer and said active layer.

10. The nitride semiconductor device according to claim 8, wherein an average mixed crystal ratio x of Al in said p-side cladding layer and said n-side cladding layer is in the range of 0<

x≦

0.05.

11. The nitride semiconductor device according to claim 8, wherein said first p-type nitride semiconductor layer adjoins to the barrier layer B_L and is grown doped with a higher p-type impurity concentration than the barrier layer B_L.

12. The nitride semiconductor device according to claim 8, wherein a guide layer is formed between said active layer and said p-side cladding layer and/or between said active layer and said n-side cladding layer.

13. The nitride semiconductor device according to claim 1, wherein a film thickness dw of the well layer is in the range of 40 Å

≦

dw≦

100 Å

while the film thickness db of the barrier layer B_L is in the range of db≧

40 Å

.

14. 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 L (L≧

2) barrier layers so that the barrier layer arranged in a position nearest to said n-type nitride semiconductor layer is denoted as barrier layer B₁ and the i-th barrier layer (i=1, 2, 3, . . . L) counted from the barrier layer B₁ toward said p-type nitride semiconductor layer is denoted as barrier layer B_i;

wherein a barrier layer B_L (i=L)is formed between the well layer and a first p-type nitride semiconductor layer formed in said p-type nitride semiconductor layer, said first p-type nitride semiconductor layer being made of a nitride semiconductor including Al and having a larger band gap energy than said active layer,

wherein the barrier layer B_L is thicker than the barrier layer B_i (i≠

L)

wherein a plurality of the barrier layers including the barrier layer B₁ and located on the n-type nitride semiconductor layer side have an n-type impurity concentration of not less than 5×

10¹⁶/cm³, and a plurality of the barrier layers including the barrier layer B_L and located on the p-type nitride semiconductor layer side have an n-type impurity concentration of less than 5×

10¹⁶/cm³.

15. The nitride semiconductor device according to claim 14, wherein the barrier layers B_i from i=1 to i=n (1<

n<

L) include an n-type impurity of not less than 5×

10¹⁶/cm³.

16. The nitride semiconductor device according to claim 14, wherein a concentration of the n-type impurity in the well layer is not more than a concentration of the n-type impurity in the barrier layer.

17. The nitride semiconductor device according to claim 14, wherein the well layer has a thickness of not less than 40 Å

.

18. The nitride semiconductor device according to claim 14, wherein at least one of the barrier layers is a stack of two or more layers of different compositions and/or impurity concentrations.

19. The nitride semiconductor device according to claim 18, wherein said stack of two or more layers includes AlaGa1−

aN (0<

a≦

1) and InbGa1−

bN (0≦

b<

1).

20. The nitride semiconductor device according to claim 14, wherein the barrier layer BL adjoins to said first p-type nitride semiconductor layer.

21. The nitride semiconductor device according to claim 14, wherein said nitride semiconductor device has a laser structure where said active layer is sandwiched by a p-side cladding layer made of a nitride semiconductor including Al and formed in said p-type nitride semiconductor layer and an n-side cladding layer made of a nitride semiconductor including Al and formed in said n-type nitride semiconductor layer.

22. The nitride semiconductor device according to claim 21, wherein said p-type nitride semiconductor layer includes a guide layer, and said first p-type nitride semiconductor layer is formed between said guide layer and said active layer.

23. The nitride semiconductor device according to claim 21, wherein an average mixed crystal ratio x of Al in said p-side cladding layer and said n-side cladding layer is in the range of 0<

x≦

0.05.

24. The nitride semiconductor device according to claim 21, wherein said first p-type nitride semiconductor layer adjoins to the barrier layer BL and is grown doped with a higher p-type impurity concentration than the barrier layer BL.

25. The nitride semiconductor device according to claim 21, wherein a guide layer is formed between said active layer and said p-side cladding layer and/or between said active layer and said n-side cladding layer.

26. The nitride semiconductor device according to claim 14, wherein a film thickness dw of the well layer is in the range of 40 Å

≦

dw≦

100 Å

while the film thickness db of the barrier layer BL is in the range of db≧

40 Å

.

27. The nitride semiconductor device according to claim 14, wherein said plurality of the barrier layers including the barrier layer B₁ and located on the n-type nitride semiconductor layer side have an n-type impurity concentration of not less than 1×

10¹⁷/cm³.