Nitride semiconductor element

• US 20040051107A1
• Filed: 09/29/2003
• Published: 03/18/2004
• Est. Priority Date: 03/28/2001
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Yanamoto, Tomoya, Nagahama, Shinichi
• Granted Patent: US 7,095,051 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02636 Selective deposition, e.g. simultaneous growth of mono- and non-monocrystalline semiconductor materials
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2302/00 Amplification / lasing wavelength
• 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 a nitride semiconductor device having an active layer 12 between a first electrically conductive type of layer and a second electrically conductive type of layer, a quantum well structure is adopted in which an active layer 12 has at least a well layer 11 formed of a nitride semiconductor containing In and Al and a barrier layer 2 formed of a nitride semiconductor containing Al, whereby a laser device excellent in emitting efficacy at a short wavelength region is obtained. It is particularly preferable that said well layer 1 is formed of Al_xIn_yGa_1-x-yN (0<x≦1<0<y≦1, x+y<1) and said barrier layer 2 is formed of Al_uIn_vGa_1-x-vN (0<u≦1, 0≦v≦1, u+v<1).

Such a light emitting device is realized to obtain excellent efficacy in emitting light of short wavelength in a region of 380 nm.

Claims

1. A nitride semiconductor device comprising an active layer provided between a first electrically conductive type of layer and a second electrically conductive type of layer, wherein said active layer has a quantum well structure including at least a well layer formed of a nitride semiconductor containing In and Al, and a barrier layer formed of a nitride semiconductor containing Al.

2. The nitride semiconductor device according to claim 1, wherein said well layer is formed of Al_xIn_yGa_1-x-yN (0<

x≦

1, 0<

y≦

1, x+y<

1) and said barrier layer is formed of Al_uIn_vGa<sub>1-u−

v</sub>N (0<

u≦

1, 0≦

v≦

1, u+v<

1).

3. The nitride semiconductor device according to claim 1 or 2, wherein a thickness of said well layer is smaller than that of the barrier layer.

4. The nitride semiconductor device according to claim 2 or 3, wherein an In composition ratio y in said well layer is in a range of not less than 0.02 and not greater than 0.05.

5. The nitride semiconductor device according to claim 2 or 3, wherein an In composition ratio y in said well layer is in a range of not less than 0.03 and not greater than 0.05.

6. The nitride semiconductor device according to any one of claims 2 to 5, wherein an emitting wavelength of said active layer is 380 nm or shorter.

7. The nitride semiconductor device according to any one of claims 1 to 6, wherein said device has a laser device structure in which said first electrically conductive type of layer has a first light guiding layer, said second electrically conductive type of layer has a second light guiding layer, and said active layer is provided between said first light guiding layer and said second light guiding layer, and

the band gap energies E_g of both said first light guiding layer and said second light guiding layer are greater than the photon energy E_p of laser light by 0.05 eV or greater (E_g−

E_p≧

0.05 eV).

8. The nitride semiconductor device according to claim 7, wherein said first light guiding layer and/or said second light guiding layer are formed of Al_xGa_1-xN (0<

x≦

1).

9. The nitride semiconductor device according to any one of claims 1 to 8, wherein said active layer emitts light of wavelength of 380 nm or shorter, and said first electrically conductive type of layer and/or said second electrically conductive type of layer are formed of Al_xGa_1-xN (0<

x≦

1).

10. A nitride semiconductor device having an active layer between a first electrically conductive type of layer and a second electrically conductive type of layer, wherein said active layer has a quantum well structure including at least a well layer formed of a nitride semiconductor containing Al, and a first barrier layer formed of a nitride semiconductor having a band gap energy larger than that of the well layer in a side near to the first electrically conductive type of layer from the well layer, and

said first electrically conductive type of layer includes a first nitride semiconductor layer having a band gap energy smaller than that of said first barrier layer, and said first nitride semiconductor layer is provided near said first barrier layer.

11. The nitride semiconductor device according to claim 10, wherein said first barrier is arranged in a side nearest to the first electrically conductive type of layer within the active layer, and said first nitride semiconductor layer is contacted with the active layer.

12. The nitride semiconductor device according to claim 10 or 11, wherein said first electrically conductive type of layer is of n-type, and said second electrically conductive type of layer is of p-type.

13. The nitride semiconductor device according to any one of claims 10 to 12, wherein an Al crystal mixing ratio X_B1 in said first barrier layer and an Al crystal mixing ratio X_w in the well layer satisfy the following relation:

X_B1−

X_W≧

0.05.

14. The nitride semiconductor device according to any one of claims 10 to 13, wherein a thickness of said first barrier layer is 30 Å

or greater.

15. The nitride semiconductor device according to any one of claims 10 to 14, wherein a waveguide is constructed of a pair of light guiding layers and an active layer therebetween, and

the light guiding layer is provided in the first electrically conductive type of layer, and has said first nitride semiconductor layer.

16. The nitride semiconductor device according to any one of claims 10 to 15, wherein said device is operable to oscillate light of wavelength of 375 nm or shorter,

an Al_xGa_1-xN quantum well layer (x≧

0) is provided between barrier layers which are formed of Al_yIn_zGa_1-y-zN (z≧

0), and

a band gap energy E_w of the well layer is larger than a band gap energy E_b of the barrier layer by 0.2 eV or greater.

17. The nitride semiconductor device according to claim 16, wherein a thickness of the well layer is 300 Å

or smaller.

18. The nitride semiconductor device according to claim 16, wherein a thickness of the barrier layer is 300 Å

or smaller.

19. The nitride semiconductor device according to claim 16, wherein said device has a SCH structure in which a light guiding layer and a cladding layer are provided apart from each other, and the band gap energy E_g of the guiding layer is greater than the photon energy E_p at oscillation by 0.05 eV.

20. The nitride semiconductor device according to claim 19, wherein the light guiding layer comprises an Al_aGa_1-aN/Al_bGa_1-bN (a≠

b) superlattice layers.

21. The nitride semiconductor device according to claim 19, wherein the cladding layer comprises an Al_cGa_1-cN/Al_dGa_1-dN (c≠

d) superlattice layers, and the band gap energy E_c of the cladding layer is greater than that of the light guiding layer.

22. The nitride semiconductor device according to claim 16, wherein said device has a GRIN structure in which a light confining layer with a stepwise varying refractive index is formed outside the quantum well layer, and non-doped layers are provided above and below the active layer.

23. The nitride semiconductor device according to any one of claims 10 to 15, wherein said device is operable to oscillate light of wavelength of 380 nm or shorter,

an active layer is provided between a first electrically conductive type of layer and a second electrically conductive type of layer, and

said active layer has a quantum well structure including at least a well layer formed of a nitride semiconductor containing In and Al, and a barrier layer formed of a nitride semiconductor containing Al.

24. The nitride semiconductor device according to claim 23, wherein said well layer is formed of Al_xIn_yGa_1-x-yN (0<

x≦

1, 0<

y≦

1, x+y<

1) and said barrier layer is formed of Al_uIn_vGa_1-u-vN (0<

u≦

1, 0≦

v≦

1, u+v<

1).

25. The nitride semiconductor device according to claim 23 or 24, wherein a thickness of said well layer is smaller than that of the barrier layer.

26. The nitride semiconductor device according to claim 24 or 25, wherein an In composition ratio y in said well layer is in a range of not less than 0.02 and not greater than 0.05.

27. The nitride semiconductor device according to claim 24 or 25, wherein an In composition ratio y in said well layer is in a range of not less than 0.03 and not greater than 0.05.

28. The nitride semiconductor device according to any one of claims 23 to 27, wherein said device has a laser device structure in which said first electrically conductive type of layer has a first light guiding layer, said second electrically conductive type of layer has a second light guiding layer, and said active layer is provided between said first light guiding layer and said second light guiding layer, and

the band gap energies E_g of both said first light guiding layer and said second light guiding layer are greater than the photon energy E_p of laser light by 0.05 eV or greater (E_g−

E_p≧

0.05 eV).

29. The nitride semiconductor device according to claim 28, wherein said first light guiding layer and/or said second light guiding layer are formed of Al_xGa_1-xN (0<

x≦

1).

30. The nitride semiconductor device according to any one of claims 23 to 29, wherein said active layer emitts light of wavelength of 380 nm or shorter, and said first electrically conductive type of layer and/or said second electrically conductive type of layer are formed of Al_xGa_1-xN (0<

x≦

1).