SEMICONDUCTOR LIGHT EMITTING ELEMENT, GROUP III NITRIDE SEMICONDUCTOR SUBSTRATE AND METHOD FOR MANUFACTURING SUCH GROUP III NITRIDE SEMICONDUCTOR SUBSTRATE

• US 20100230713A1
• Filed: 01/19/2007
• Published: 09/16/2010
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hasegawa, Yoshiaki, Kitaoka, Yasuo, Kawaguchi, Yasutoshi, Takahashi, Yasuhito, Minemoto, Hisashi
• Granted Patent: US 8,231,726 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: C30B 19/02 using molten solvents, e.g. flux
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/0206 Substrates, e.g. growth, shape, material, removal or bonding; specific crystal orientation H01S5/3202
• 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 5/32341 blue laser based on GaN or GaP

Abstract

An object of the present invention is to obtain, with respect to a semiconductor light-emitting element using a group III nitride semiconductor substrate, a semiconductor light-emitting element having an excellent light extraction property by selecting a specific substrate dopant and controlling the concentration thereof. The semiconductor light-emitting element comprises a substrate composed of a group III nitride semiconductor comprising germanium (Ge) as a dopant, an n-type semiconductor layer composed of a group III nitride semiconductor formed on the substrate, an active layer composed of a group III nitride semiconductor formed on the n-type semiconductor layer, and a p-type semiconductor layer composed of a group III nitride semiconductor formed on the active layer in which the substrate has a germanium (Ge) concentration of 2×10¹⁷ to 2×10¹⁹ cm⁻³. The substrate is produced in a nitrogen-containing atmosphere using a melt comprising at least a group III element, an alkali or alkaline earth metal, and germanium (Ge) and nitrogen.

Claims

1. A semiconductor light-emitting element comprising:

a substrate comprising a group III nitride semiconductor composed of germanium (Ge) as a dopant;

an n-type semiconductor layer composed of a group III nitride semiconductor formed on the substrate;

an active layer composed of a group III nitride semiconductor formed on the n-type semiconductor layer; and

a p-type semiconductor layer composed of a group III nitride semiconductor formed on the active layer,

the substrate having a germanium (Ge) concentration of 2×

10¹⁷ to 2×

10¹⁹ cm<sup>−

3</sup>, and the substrate being produced in a nitrogen-containing atmosphere using a melt comprising at least a group III element, an alkali or alkaline earth metal, germanium (Ge) and nitrogen.

2. The semiconductor light-emitting element according to claim 1, wherein the germanium concentration in the thickness direction of the substrate is substantially uniform.

3. The semiconductor light-emitting element according to claim 1, wherein the n-type semiconductor layer comprises germanium (Ge) as a dopant.

4. The semiconductor light-emitting element according to claim 3, wherein the n-type semiconductor layer has a germanium (Ge) concentration of 2×

10¹⁷ to 2×

10¹⁹ cm<sup>−

3</sup>.

5. The semiconductor light-emitting element according to claim 2, wherein the substrate has a germanium (Ge) concentration of 1×

10¹⁸ to 2×

10¹⁹ cm<sup>−

3</sup> and the semiconductor light-emitting element further comprises a resonator.

6. The semiconductor light-emitting element according to claim 5, wherein the substrate has an optical absorption coefficient at the center wavelength of light emitted from the active layer of 70 cm⁻

1 or greater.

7. The semiconductor light-emitting element according to claim 6, wherein the substrate further comprises at least one element selected from the group consisting of barium (Ba), strontium (Sr), ytterbium (Yb) and europium (Eu).

8. The semiconductor light-emitting element according to claim 2, wherein the germanium (Ge) concentration in the substrate is 2×

10¹⁷ to 5×

10¹⁸ cm<sup>−

3</sup> and the semiconductor light-emitting element is a surface-emitting type which outputs from a substrate side light emitted from the active layer.

9. The semiconductor light-emitting element according to claim 8, wherein the substrate has an optical absorption coefficient at the center wavelength of light emitted from the active layer of 5 cm⁻

1 or less.

10. A group III nitride semiconductor substrate comprising germanium (Ge) as a dopant,

the substrate having a germanium (Ge) concentration of 2×

10¹⁷ to 2×

10¹⁹ cm<sup>−

3</sup>, and being produced in a nitrogen-containing atmosphere using a melt comprising at least a group III element, an alkali or alkaline earth metal, germanium (Ge) and nitrogen.

11. The group III nitride semiconductor substrate according to claim 10 having a substantially uniform germanium concentration in a thickness direction.

12. The group III nitride semiconductor substrate according to claim 10 having a dislocation density of not more than 1×

10⁵ cm<sup>−

2</sup>.

13. The group III nitride semiconductor substrate according to claim 10 having a diameter of 20 mm or greater.

14. The group III nitride semiconductor substrate according to claim 10 having a thickness of 100 μ

m or greater.

15. The group III nitride semiconductor substrate according to claim 10 further comprising at least one element selected from the group consisting of barium (Ba), strontium (Sr), ytterbium (Yb) and europium (Eu).

16. A method for manufacturing a group III nitride semiconductor substrate comprising a growing step in which a surface of a seed crystal is brought into contact in a nitrogen-containing atmosphere with a melt comprising at least a group III element, an alkali or alkaline earth metal, germanium (Ge) and nitrogen to react the group III element with the nitrogen and grow a group III nitride crystal on the seed crystal.

17. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein the germanium (Ge) content relative to the group III element content in the melt is 0.05 mol % to 15 mol %.

18. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein the germanium (Ge) content relative to the group III element content in the melt is 0.5 mol % to 10 mol %.

19. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein the germanium (Ge) concentration in a thickness direction of the group III nitride crystal is substantially uniform.

20. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein in the growing step the group III nitride crystal is grown while reducing a growth rate of the group III nitride crystal from a surface of the seed crystal toward a surface of the group III nitride crystal.

21. The method for manufacturing a group III nitride semiconductor substrate according to claim 20, wherein growth temperature is increased by 3 to 20°

C. after crystal growth has started in the growing step.

22. The method for manufacturing a group III nitride semiconductor substrate according to claim 20, wherein growth pressure is lowered by 0.03 to 0.5 MPa after crystal growth has started in the growing step.

23. The method for manufacturing a group III nitride semiconductor substrate according to claim 17, wherein the concentration of dopant germanium is at its solid solubility limit.

24. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein ambient temperature in the growing step is 750 to 1000°

C.

25. The method for manufacturing a group III nitride semiconductor substrate according to claim 16, wherein the melt further comprises at least one element selected from the group consisting of barium (Ba), strontium (Sr), ytterbium (Yb) and europium (Eu).