GROUP-III NITRIDE SEMICONDUCTOR DEVICE, METHOD FOR FABRICATING GROUP-III NITRIDE SEMICONDUCTOR DEVICE, AND EPITAXIAL SUBSTRATE

• US 20120112203A1
• Filed: 11/04/2011
• Published: 05/10/2012
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: ENYA, Yohei, KYONO, Takashi, SUMITOMO, Takamichi, YOSHIZUMI, Yusuke, NISHIZUKA, Koji
• Granted Patent: US 8,809,868 B2
• Time in Patent Office: Days
• US Class Current: 257/76
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02505 consisting of more than two layers
• CPC Class Codes: H01L 21/0254 Nitrides
• 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 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/325 characterised by the doping materials
• CPC Class Codes: H01S 2302/00 Amplification / lasing wavelength
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/028 Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/2031 characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/320275 semi-polar orientation
• CPC Class Codes: H01S 5/3213 asymmetric clading layers
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

Provided is a Group III nitride semiconductor device, which comprises an electrically conductive substrate including a primary surface comprised of a first gallium nitride based semiconductor, and a Group III nitride semiconductor region including a first p-type gallium nitride based semiconductor layer and provided on the primary surface. The primary surface of the substrate is inclined at an angle in the range of not less than 50 degrees, and less than 130 degrees from a plane perpendicular to a reference axis extending along the c-axis of the first gallium nitride based semiconductor, an oxygen concentration Noxg of the first p-type gallium nitride based semiconductor layer is not more than 5×10¹⁷ cm⁻³, and a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the first p-type gallium nitride based semiconductor layer is not more than 1/10.

Claims

1. A Group III nitride semiconductor device comprising:

a substrate having an electrically conductivity, the substrate including a primary surface, the primary surface comprising a first gallium nitride based semiconductor; and

a Group III nitride semiconductor region including a first p-type gallium nitride based semiconductor layer and provided on the primary surface,

the primary surface of the substrate being inclined at an angle in a range of not less than 50 degrees and less than 130 degrees from a plane perpendicular to a reference axis, the reference axis extending along a c-axis of the first gallium nitride based semiconductor,

an oxygen concentration Noxg of the first p-type gallium nitride based semiconductor layer being not more than 5×

10¹⁷ cm<sup>−

3</sup>, and a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the first p-type gallium nitride based semiconductor layer being not more than 1/10.

2. The Group III nitride semiconductor device according to claim 1, wherein the first p-type gallium nitride based semiconductor layer does not contain indium as a Group III constituent element.

3. The Group III nitride semiconductor device according to claim 1, further comprising:

an n-type gallium nitride based semiconductor layer provided on the primary surface; and

a gallium nitride based semiconductor layer for a light emitting layer,

wherein the light emitting layer is provided between the p-type gallium nitride based semiconductor layer and the n-type gallium nitride based semiconductor layer, and

wherein the Group III nitride semiconductor device comprises a light emitting device.

4. The Group III nitride semiconductor device according to claim 3, wherein an emission wavelength of the light emitting layer is not less than 440 nm and not more than 600 nm.

5. The Group III nitride semiconductor device according to claim 3, wherein an emission wavelength of the light emitting layer is not less than 490 nm and not more than 600 nm.

6. The Group III nitride semiconductor device according to claim 3, further comprising an electrode making contact with the Group III nitride semiconductor region,

wherein the Group III nitride semiconductor region includes a contact layer making contact with the electrode, and a p-type Group III nitride semiconductor region,

wherein the p-type Group III nitride semiconductor region is provided between the contact layer and the light emitting layer,

wherein the p-type Group III nitride semiconductor region makes a first junction with the contact layer and a second junction with the light emitting layer,

wherein an oxygen concentration of the p-type Group III nitride semiconductor region is not more than 5×

10¹⁷ cm<sup>−

3</sup>, and

wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the p-type Group III nitride semiconductor region is not more than 1/10.

7. The Group III nitride semiconductor device according to claim 1, wherein the first p-type gallium nitride based semiconductor layer comprises any one of GaN, InGaN, AlGaN, and InAlGaN.

8. The Group III nitride semiconductor device according to claim 1, wherein the first p-type gallium nitride based semiconductor layer comprises either one of GaN and AlGaN.

9. The Group III nitride semiconductor device according to claim 1, wherein a carbon concentration of the first p-type gallium nitride based semiconductor layer is not more than 1×

10¹⁷ cm<sup>−

3</sup>.

10. The Group III nitride semiconductor device according to claim 1, wherein the Group III nitride semiconductor region further includes a second p-type gallium nitride based semiconductor layer provided on the primary surface,

wherein an oxygen concentration of the second p-type gallium nitride based semiconductor layer is not more than 5×

10¹⁷ cm<sup>−

3</sup>,

wherein the second p-type gallium nitride based semiconductor layer contains indium as a Group III constituent element, and wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the second p-type gallium nitride based semiconductor layer is not more than 1/10.

11. A method for fabricating a Group III nitride semiconductor device, comprising the steps of:

preparing a substrate having an electrically conductivity, the substrate including a primary surface, the primary surface comprising a first gallium nitride based semiconductor; and

growing a Group III nitride semiconductor region on the primary surface, the Group III nitride semiconductor region including a first p-type gallium nitride based semiconductor layer,

in growth of the first p-type gallium nitride based semiconductor layer, a source gas for a Group III constituent element and a Group V constituent element of the first p-type gallium nitride based semiconductor layer, and a first atmosphere gas being supplied into a growth reactor,

nitrogen being used as the first atmosphere gas,

the primary surface of the substrate being inclined at an angle in a range of not less than 50 degrees and less than 130 degrees from a plane perpendicular to a reference axis, the reference axis extending along a c-axis of the first gallium nitride based semiconductor,

an oxygen concentration Noxg of the first p-type gallium nitride based semiconductor layer being not more than 5×

10¹⁷ cm<sup>−

3</sup>, and

a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the first p-type gallium nitride based semiconductor layer being not more than 1/10.

12. The method for fabricating the Group III nitride semiconductor device according to claim 11, wherein the first p-type gallium nitride based semiconductor layer does not contain indium as a Group III constituent element.

13. The method for fabricating the Group III nitride semiconductor device according to claim 11, further comprising the steps of:

growing an n-type gallium nitride based semiconductor layer on the primary surface; and

growing a gallium nitride based semiconductor layer for an active layer on the primary surface,

wherein the active layer is provided between the p-type gallium nitride based semiconductor layer and the n-type gallium nitride based semiconductor layer, and

wherein the Group III nitride semiconductor device comprises a light emitting device.

14. The method for fabricating the Group III nitride semiconductor device according to claim 13, wherein an emission wavelength of the active layer is not less than 440 nm and not more than 600 nm.

15. The method for fabricating the Group III nitride semiconductor device according to claim 13, wherein an emission wavelength of the active layer is not less than 490 nm and not more than 600 nm.

16. The method for fabricating the Group III nitride semiconductor device according to claim 13, further comprising the step of forming an electrode making contact with the Group III nitride semiconductor region,

wherein the Group III nitride semiconductor region includes a contact layer making contact with the electrode, and a p-type Group III nitride semiconductor lamination,

wherein the p-type Group III nitride semiconductor lamination is provided between the contact layer and the active layer,

wherein the p-type Group III nitride semiconductor lamination makes a first junction with the contact layer and a second junction with the active layer,

wherein in growth of each p-type gallium nitride based semiconductor layer in the p-type Group III nitride semiconductor lamination, a source gas for a Group III constituent element and a Group V constituent element of each p-type gallium nitride based semiconductor layer, and a second atmosphere gas are supplied into the growth reactor,

wherein nitrogen is used as the second atmosphere gas,

wherein an oxygen concentration of the p-type Group III nitride semiconductor lamination is not more than 5×

10¹⁷ cm<sup>−

3</sup>, and

wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the p-type Group III nitride semiconductor lamination is not more than 1/10.

17. The method for fabricating the Group III nitride semiconductor device according to claim 11, wherein the first p-type gallium nitride based semiconductor layer comprises any one of GaN, InGaN, AlGaN, and InAlGaN.

18. The method for fabricating the Group III nitride semiconductor device according to claim 11, wherein the first p-type gallium nitride based semiconductor layer comprises either one of GaN and AlGaN.

19. The method for fabricating the Group III nitride semiconductor device according to claim 11, wherein a carbon concentration of the first p-type gallium nitride based semiconductor layer is not more than 1×

10¹⁷ cm<sup>−

3</sup>.

20. The method for fabricating the Group III nitride semiconductor device according to claim 11,

wherein the Group III nitride semiconductor region further includes a second p-type gallium nitride based semiconductor layer,

wherein the second p-type gallium nitride based semiconductor layer contains indium as a Group III constituent element,

wherein in growth of the second p-type gallium nitride based semiconductor layer, a source gas for a Group III constituent element and a Group V constituent element of the second p-type gallium nitride based semiconductor layer, and a second atmosphere gas are supplied into the growth reactor,

wherein nitrogen is used as the second atmosphere gas,

wherein an oxygen concentration of the second p-type gallium nitride based semiconductor layer is not more than 5×

10¹⁷ cm<sup>−

3</sup>, and

wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the second p-type gallium nitride based semiconductor layer is not more than 1/10.

21. The method for fabricating the Group III nitride semiconductor device according to claim 11, wherein a surface roughness of the Group III nitride semiconductor region is not more than 1 nm in an arithmetic average roughness.

22. An epitaxial substrate for a Group III nitride semiconductor device, comprising:

a substrate having an electrically conductivity, the substrate including a primary surface, and the primary surface comprising a first gallium nitride based semiconductor; and

a Group III nitride semiconductor region including a first p-type gallium nitride based semiconductor layer and provided on the primary surface,

the primary surface of the substrate being inclined at an angle in a range of not less than 50 degrees and less than 130 degrees from a plane perpendicular to a reference axis, the reference axis extending along a c-axis of the first gallium nitride based semiconductor, an oxygen concentration Noxg of the first p-type gallium nitride based semiconductor layer being not more than 5×

10¹⁷ cm<sup>−

3</sup>, and a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the first p-type gallium nitride based semiconductor layer being not more than 1/10.

23. The epitaxial substrate according to claim 22, wherein the first p-type gallium nitride based semiconductor layer does not contain indium as a Group III constituent element.

24. The epitaxial substrate according to claim 22, further comprising:

an n-type gallium nitride based semiconductor layer provided on the primary surface; and

a gallium nitride based semiconductor layer for a light emitting layer,

wherein the light emitting layer is provided between the p-type gallium nitride based semiconductor layer and the n-type gallium nitride based semiconductor layer, and

wherein the Group III nitride semiconductor device comprises a light emitting device.

25. The epitaxial substrate according to claim 24, wherein an emission wavelength of the light emitting layer is not less than 440 nm and not more than 600 nm.

26. The epitaxial substrate according to claim 24, wherein an emission wavelength of the light emitting layer is not less than 490 nm and not more than 600 nm.

27. The epitaxial substrate according to claim 24, wherein the whole of the Group III nitride semiconductor region has p-type conductivity,

wherein an oxygen concentration of the Group III nitride semiconductor region is not more than 5×

10¹⁷ cm<sup>−

3</sup>, and wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the Group III nitride semiconductor region is not more than 1/10.

28. The epitaxial substrate according to claim 22, wherein the first p-type gallium nitride based semiconductor layer comprises any one of GaN, InGaN, AlGaN, and InAlGaN.

29. The epitaxial substrate according to claim 23, wherein the first p-type gallium nitride based semiconductor layer comprises either one of GaN and AlGaN.

30. The epitaxial substrate according to claim 22, wherein a carbon concentration of the first p-type gallium nitride based semiconductor layer is not more than 1×

10¹⁷ cm <sup>−

3</sup>.

31. The epitaxial substrate according to claim 22, wherein the Group III nitride semiconductor region further includes a second p-type gallium nitride based semiconductor layer provided on the primary surface,

wherein an oxygen concentration of the second p-type gallium nitride based semiconductor layer is not more than 5×

10¹⁷ cm<sup>−

3</sup>,

wherein the second p-type gallium nitride based semiconductor layer contains indium as a Group III constituent element, and

wherein a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the second p-type gallium nitride based semiconductor layer is not more than 1/10.

32. The epitaxial substrate according to claim 22, wherein a surface roughness of the epitaxial substrate is not more than 1 nm in an arithmetic average roughness.