GROUP III NITRIDE SEMICONDUCTOR DEVICE, METHOD OF FABRICATING GROUP III NITRIDE SEMICONDUCTOR DEVICE

• US 20130009202A1
• Filed: 06/29/2012
• Published: 01/10/2013
• Est. Priority Date: 06/29/2011
• Status: Abandoned Application

• Current Assignee: Sony Corporation (Sony Group Corp.), Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: ENYA, Yohei, YOSHIZUMI, Yusuke, SUMITOMO, Takamichi, UENO, Masaki, YANASHIMA, Katsunori, TASAI, Kunihiko, NAKAJIMA, Hiroshi, KYONO, Takashi
• Application Number:
  US13/538,513
• Publication Number:
  US 20130009202A1
• 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 21/0254 Nitrides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• 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 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/0014 Measuring characteristics or properties thereof measuring techniques per se G01J, G01K, G01N, G01R
• CPC Class Codes: H01S 5/0202 Cleaving
• CPC Class Codes: H01S 5/0421 characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/320275 semi-polar orientation
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A group-III nitride semiconductor device includes a light emitting layer emitting light of a wavelength in the range of 480 to 600 nm; a first contact layer over the light emitting layer; a second contact layer in direct contact with the first contact layer; and a metal electrode in direct contact with the second contact layer. The first and second contact layers comprise a p-type gallium nitride-based semiconductor. The p-type dopant concentration of the first contact layer is lower than that of the second contact layer. The light emitting layer comprises a gallium nitride-based semiconductor. The interface between the first and second contact layers tilts at an angle of not less than 50 degrees and smaller than 130 degrees from a plane orthogonal to a reference axis extending along the c-axis. The second contact layer has a thickness within the range of 1 to 50 nm.

Claims

1. A group-III nitride semiconductor device comprising:

a gallium nitride-based semiconductor light emitting layer;

a first contact layer provided on the light emitting layer;

a second contact layer provided on the first contact layer and in direct contact with the first contact layer; and

a metal electrode provided on the second contact layer and in direct contact with the second contact layer;

a gallium nitride-based semiconductor of the first contact layer being the same as a gallium nitride-based semiconductor of the second contact layer, the first contact layer and the second contact layer having a p-type conductivity,

a p-type dopant concentration of the first contact layer being lower than a p-type dopant concentration of the second contact layer,

an interface between the first contact layer and the second contact layer tilting at an angle of not less than 50 degrees and smaller than 130 degrees from a plane orthogonal to a reference axis, the reference axis extending along a c-axis thereof,

a wavelength of light emitted from the light emitting layer being in a range of 480 to 600 nm, and

the second contact layer having a thickness in a range of 1 to 50 nm.

2. The group-III nitride semiconductor device according to claim 1, wherein the second contact layer has a thickness in a range of 1 to 20 nm.

3. The group-III nitride semiconductor device according to claim 1, further comprising a cladding layer of a p-type gallium nitride-based semiconductor,

wherein

the cladding layer is provided between the light emitting layer and the first contact layer,

a bandgap of the cladding layer is larger than a bandgap of the first contact layer, and

the first contact layer is in direct contact with the cladding layer.

4. The group-III nitride semiconductor device according to claim 3, further comprising a substrate, the substrate comprising a gallium nitride-based semiconductor,

wherein

the light emitting layer, the cladding layer, the first contact layer, the second contact layer, and the metal electrode are arranged in sequence on a primary surface of the substrate, and

the primary surface tilts at an angle of not less than 50 degrees and smaller than 130 degrees from a plane orthogonal to the reference axis.

5. The group-III nitride semiconductor device according to claim 1, wherein a p-type dopant concentration of the first contact layer is not more than 5×

10²⁰ cm<sup>−

3</sup>.

6. The group-III nitride semiconductor device according to claim 1, wherein a p-type dopant concentration of the second contact layer is in a range of 1×

10²⁰ to 1×

10²¹ cm<sup>−

3</sup>.

7. The group-III nitride semiconductor device according to claim 1, wherein a p-type dopant concentration of the first contact layer is in a range of 5×

10¹⁸ to 5×

10¹⁹ cm<sup>−

3</sup>.

8. The group-111 nitride semiconductor device according to claim 5, wherein the p-type dopant comprises magnesium.

9. The group-III nitride semiconductor device according to claim 1, wherein the first contact layer comprises gallium nitride and the second contact layer comprise gallium nitride.

10. The group-III nitride semiconductor device according to claim 1, wherein the first contact layer and the second contact layer comprise In_xAl_yGa_1-x-yN (0≦

x≦

1, 0≦

y≦

1, 0≦

1-x-y).

11. The group-III nitride semiconductor device according to claim 1, wherein the light emitting layer comprises In_xGa_1-xN (0.15≦

x<

0.50).

12. The group-III nitride semiconductor device according to claim 1, wherein the metal electrode comprises one of palladium, gold, and nickel and gold.

25. The group-III nitride semiconductor device according to claim 1, wherein a carbon impurity concentration of the first contact layer is not more than 1×

10¹⁷ cm<sup>−

3</sup>.

26. The group-III nitride semiconductor device according to claim 4, wherein the primary surface of the substrate tilts at an angle of not less than 70 degrees and smaller than 80 degrees from a plane orthogonal to the reference axis.

27. The group-III nitride semiconductor device according to claim 4, wherein the primary surface of the substrate tilts at an angle of not less than 100 degrees and smaller than 110 degrees from a surface orthogonal to the reference axis.

13. A method of fabricating a group-III nitride semiconductor device, comprising the steps of:

growing a light emitting layer, the light emitting layer comprising a gallium nitride-based semiconductor;

growing a first contact layer on the light emitting layer, the first contact layer comprising a p-type gallium nitride-based semiconductor;

after changing amount of p-type dopant supplied in the growth of the first contact layer, growing a second contact layer on the first contact layer, the second contact layer comprising a p-type gallium nitride-based semiconductor; and

forming a metal electrode on the second contact layer,

a p-type gallium nitride-based semiconductor of the first contact layer being the same as a p-type gallium nitride-based semiconductor of the second contact layer,

amount of p-type dopant supplied to a growth reactor in the growth of the second contact layer being larger than amount of p-type dopant supplied to a growth reactor in the growth of the first contact layer,

a growth temperature for the first contact layer and the second contact layer being higher than a growth temperature of an active layer in the light emitting layer,

a difference between the growth temperature for the first contact layer and the second contact layer and the growth temperature for the active layer being in a range of 100 degrees Celsius to 350 degrees Celsius,

the second contact layer being in direct contact with the metal electrode,

the first contact layer being in direct contact with the second layer,

an interface between the first contact layer and the second contact layer tilting at an angle of not less than 50 degrees and smaller than 130 degrees from a plane orthogonal to a reference axis, the reference axis extending along a c-axis thereof,

the light emitting layer emitting light, the light having a wavelength in a range of 480 to 600 nm, and

the second contact layer has a thickness in a range of 1 to 50 nm.

14. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the second contact layer has a thickness in a range of 1 to 20 nm.

15. The method of fabricating a group-III nitride semiconductor device according to claim 13, further comprising the step of growing a cladding layer of a p-type gallium nitride-based semiconductor,

wherein

the cladding layer being grown after the light emitting layer has been grown,

the first contact layer and the second contact layer being grown after the cladding layer has been grown,

the cladding layer is provided between the light emitting layer and the first contact layer,

a bandgap of the cladding layer being greater than a bandgap of the first contact layer, and

the first contact layer being in direct contact with the cladding layer.

16. The method of fabricating a group-III nitride semiconductor device according to claim 15, further comprising the step of preparing a substrate, the substrate comprising a gallium nitride-based semiconductor,

wherein

the cladding layer is grown on the substrate,

the light emitting layer, the cladding layer, the first contact layer, the second contact layer, and the metal electrode are arranged in sequence on a primary surface of the substrate, and

the primary surface tilting at an angle of not less than 50 degrees and smaller than 130 degrees from a plane orthogonal to the reference axis.

17. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein a p-type dopant concentration of the first contact layer is 5×

10²⁰ cm<sup>−

3</sup> or lower.

18. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein a p-type dopant concentration of the second contact layer is in a range of 1×

10²⁰ to 1×

10²¹ cm<sup>−

3</sup>.

19. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the p-type dopant concentration of the first contact layer is within the range of 5×

10¹⁸ to 5×

10¹⁹ cm<sup>−

3</sup>.

20. The method of fabricating a group-III nitride semiconductor device according to claim 17, wherein the p-type dopant comprises magnesium.

21. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the first contact layer comprises gallium nitride and the second contact layer comprises gallium nitride.

22. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the first contact layer and the second contact layer comprise In_xAl_yGa_1-x-yN (0≦

x≦

1, 0≦

y≦

1, 0≦

1-x-y).

23. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the light emitting layer comprises In_xGa_1-xN (0.15≦

x<

0.50).

24. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the metal electrode comprises one of palladium, gold, and an alloy of nickel and gold.

28. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein

a growth rate of the first contact layer is not larger than 1 μ

m/hour,

a growth rate of the second contact layer is not larger than 0.1 μ

m/hour, and

the growth rate of the second contact layer is lower than the growth rate of the first contact layer.

29. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein the first contact layer and the second contact layer are grown in an atmosphere having a hydrogen content of not less than 20%.

30. The method of fabricating a group-M nitride semiconductor device according to claim 13, wherein a carbon impurity concentration of the first contact layer is not more than 1×

10¹⁷ cm<sup>−

3</sup>.

31. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein a difference between the growth temperature of the first contact layer and second contact layer and the growth temperature of the active layer is in a range of 100 degrees Celsius to 250 degrees Celsius,

32. The method of fabricating a group-III nitride semiconductor device according to claim 16, wherein the primary surface of the substrate tilts at an angle of not less than 70 degrees and smaller than 80 degrees from a plane orthogonal to the reference axis.

33. The method of fabricating a group-III nitride semiconductor device according to claim 16, wherein the primary surface of the substrate tilts at an angle of not less than 100 degrees and smaller than 110 degrees from a plane orthogonal to the reference axis.

34. The method of fabricating a group-III nitride semiconductor device according to claim 13, wherein a growth temperature of the active layer is not less than 650 degrees Celsius and lower than 800 degrees Celsius.