Nitride semiconductor device and method for manufacturing the same

Abstract

A nitride semiconductor device includes: a substrate having a principal surface; a first nitride semiconductor layer formed on the principal surface of the substrate and includes one or more convex portions whose side surfaces are vertical to the principal surface; and a second nitride semiconductor layer selectively grown on the side surfaces of the one or more convex portions of the first nitride semiconductor layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view illustrating a light emitting diode as a nitride semiconductor device of a first embodiment of the present invention.

FIGS. 2A to 2D are sectional views illustrating the steps of a method for manufacturing the nitride semiconductor device of the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view partially illustrating first and second p-type contact layers of FIG. 2B during the manufacture of the nitride semiconductor device of the first embodiment of the present invention.

FIG. 4 is an oblique view illustrating a nitride semiconductor device of a second embodiment of the present invention.

FIG. 5 is an oblique view illustrating a semiconductor laser device as a nitride semiconductor device of a third embodiment of the present invention.

FIGS. 6A to 6D are sectional views illustrating the steps of a method for manufacturing the nitride semiconductor device of the third embodiment of the present invention and FIGS. 6E and 6F are oblique views illustrating the steps of the method for manufacturing the nitride semiconductor device of the third embodiment of the present invention.

FIG. 7 is a sectional view illustrating a semiconductor laser device as a nitride semiconductor device of a fourth embodiment of the present invention.

FIGS. 8A to 8D are sectional views illustrating the steps of a method for manufacturing the nitride semiconductor device of the fourth embodiment of the present invention.

FIG. 9 is a sectional view illustrating one of the steps of a method for manufacturing a first modification of the nitride semiconductor device of the fourth embodiment of the present invention.

FIGS. 10A to 10C are oblique views illustrating the steps of a method for manufacturing a second modification of the nitride semiconductor device of the fourth embodiment of the present invention. FIG. 10D is a sectional view taken along the line Xd-Xd of FIG. 10C.

FIG. 11 is an oblique view illustrating one of the steps of a method for manufacturing a third modification of the nitride semiconductor device of the fourth embodiment of the present invention.

FIG. 12 is an oblique view illustrating one of the steps of a method for manufacturing a fourth modification of the nitride semiconductor device of the fourth embodiment of the present invention.

FIG. 13 is a sectional view illustrating a fifth modification of the nitride semiconductor device of the fourth embodiment of the present invention.

FIG. 14 is a sectional view a first conventional example of a light emitting diode using a nitride semiconductor.

Claims

1. A nitride semiconductor device comprising: a substrate having a principal surface;a first nitride semiconductor layer formed on the principal surface of the substrate and includes one or more convex portions whose side surfaces are vertical to the principal surface; anda second nitride semiconductor layer selectively grown on the side surfaces of the one or more convex portions of the first nitride semiconductor layer.

2. The nitride semiconductor device of claim 1, wherein the side surfaces of the one or more convex portions are provided by forming protrusions and depressions in at least a top portion of the first nitride semiconductor layer,the first and second nitride semiconductor layers have a p-type conductivity andthe second nitride semiconductor layer has a higher p-type carrier concentration than the first nitride semiconductor layer.

3. The nitride semiconductor device of claim 1, wherein the side surfaces of the one or more convex portions are provided by forming protrusions and depressions in at least a top portion of the first nitride semiconductor layer,the first and second nitride semiconductor layers have a p-type conductivity andthe second nitride semiconductor layer has a lower residual hydrogen concentration than the first nitride semiconductor layer.

4. The nitride semiconductor device of claim 1, wherein the side surfaces of the one or more convex portions are provided by forming protrusions and depressions in at least a top portion of the first nitride semiconductor layer,the first and second nitride semiconductor layers have a p-type conductivity andthe composition of the first nitride semiconductor layer is AlxGa1-xN (wherein 0≦x≦1) and the composition of the second nitride semiconductor layer is AlxGa1-xNyPzAs1-y-z (wherein 0≦x, y, z≦1 and 0<y+z<1).

5. The nitride semiconductor device of claim 1, wherein the side surfaces of the one or more convex portions are provided by forming protrusions and depressions in at least a top portion of the first nitride semiconductor layer,the first and second nitride semiconductor layers have a p-type conductivity andthe second nitride semiconductor layer has a higher refractive index than the first nitride semiconductor layer.

6. The nitride semiconductor device of claim 2 further comprising: an electrode formed on the second nitride semiconductor layer in contact with the second nitride semiconductor layer, whereinthe second nitride semiconductor layer is formed to bury the protrusions and depressions.

7. The nitride semiconductor device of claim 2, wherein the protrusions and depressions provide a photonic crystal structure.

8. The nitride semiconductor device of claim 2, wherein the first and second nitride semiconductor layers are configured to form a ridge stripe extending in a certain direction.

9. The nitride semiconductor device of claim 8, wherein the protrusions and depressions extend in a direction vertical to the certain direction and are arranged periodically along the certain direction.

10. The nitride semiconductor device of claim 1, wherein the side surfaces of the one or more convex portions of the first nitride semiconductor layer have a (000-1), (11-20) or (1-100) plane orientation.

11. The nitride semiconductor device of claim 1, wherein the first nitride semiconductor layer has a first conductivity type and includes a ridge stripe extending in a certain direction,the second nitride semiconductor layer is an overhanging semiconductor layer which is grown on the side surfaces of the ridge stripe of the first nitride semiconductor layer in a direction parallel to the principal surface of the substrate andthe nitride semiconductor device further includes a third nitride semiconductor layer formed to cover the top surfaces of the ridge stripe and the overhanging semiconductor layer and includes an active layer.

12. The nitride semiconductor device of claim 11, wherein the overhanging semiconductor layer is insulative or has a second conductivity type.

13. The nitride semiconductor device of claim 11, wherein part of the overhanging semiconductor layer has a larger band gap than the first nitride semiconductor layer.

14. The nitride semiconductor device of claim 11, wherein the composition of the overhanging semiconductor layer is varied periodically in a direction away from the side surfaces of the ridge stripe of the first nitride semiconductor layer.

15. The nitride semiconductor device of claim 11, wherein the composition of the overhanging nitride semiconductor layer is varied continuously in a direction away from the side surfaces of the ridge stripe of the first nitride semiconductor layer such that the band gap of the overhanging semiconductor layer is continuously increased.

16. The nitride semiconductor device of claim 11, wherein a gap is formed between parts of the first nitride semiconductor layer on the sides of the ridge stripe and the overhanging semiconductor layer.

17. The nitride semiconductor device of claim 11, wherein the top surface of the ridge stripe of the first nitride semiconductor layer has a (0001) plane orientation.

18. The nitride semiconductor device of claim 11, wherein the top surface of the ridge stripe of the first nitride semiconductor layer has periodic protrusions and depressions.

19. The nitride semiconductor device of claim 11, wherein the width of the ridge stripe of the first nitride semiconductor layer is varied continuously along the certain direction.

20. The nitride semiconductor device of claim 11, wherein the width of the ridge stripe of the first nitride semiconductor layer is varied periodically along the certain direction.

21. The nitride semiconductor device of claim 11, wherein part of the first nitride semiconductor layer and the other part of the first nitride semiconductor layer aligned along the direction vertical to the principal surface of the substrate have compositions different from each other.

22. The nitride semiconductor device of claim 11, wherein the side surfaces of the ridge stripe of the first nitride semiconductor layer have at least a single plane orientation.

23. The nitride semiconductor device of claim 11, wherein the top surface of the ridge stripe of the first nitride semiconductor layer is lower than the top surface of the overhanging semiconductor layer.

24. The nitride semiconductor device of claim 11, wherein part of the active layer located above the ridge stripe has a longer adsorption edge wavelength than part of the active layer located above the overhanging semiconductor layer.

25. The nitride semiconductor device of claim 11, wherein the overhanging semiconductor layer has a lower residual hydrogen concentration than the first nitride semiconductor layer.

26. The nitride semiconductor device of claim 1, wherein the second nitride semiconductor layer is formed using an organic nitride material as a nitrogen source.

27. The nitride semiconductor device of claim 26, wherein the organic nitride material contains asymmetric dimethylhydrazine or asymmetric dibutylhydrazine as a main ingredient.

28. A method for manufacturing a nitride semiconductor device comprising the steps of: forming a first nitride semiconductor layer on a substrate;forming one or more convex portions in at least a top portion of the first nitride semiconductor layer; andselectively growing a second nitride semiconductor layer on the side surfaces of the one or more convex portions of the nitride semiconductor layer using an organic nitride material as a nitrogen source after the step of forming the one or more convex portions.

29. The method of claim 28, wherein the side surfaces of the one or more convex portions of the first nitride semiconductor layer have a (000-1), (11-20) or (1-100) plane orientation.

30. The method of claim 28, wherein the first and second nitride semiconductor layers have a p-type conductivity andat least one of phosphorus and arsenic is added to the second nitride semiconductor layer during the step of forming the second nitride semiconductor layer.

31. The method of claim 30, wherein an organic phosphorus material is used as a phosphorus source and an organic arsenic material is used as an arsenic source in the step of forming the second nitride semiconductor layer.

32. The method of claim 28, wherein the organic nitride material is asymmetric dimethylhydrazine or asymmetric dibutylhydrazine.

33. A method for manufacturing a nitride semiconductor device comprising the steps of: forming on a substrate a first nitride semiconductor layer whose principal surface has a (000-1), (11-20) or (1-100) plane orientation andgrowing a second nitride semiconductor layer on the first nitride semiconductor layer using an organic nitride material as a nitrogen source after the step of forming the first nitride semiconductor layer.

34. The method of claim 33, wherein the first and second nitride semiconductor layers have a p-type conductivity andat least one of phosphorus and arsenic is added to the second nitride semiconductor layer in the step of forming the second nitride semiconductor layer.

35. The method of claim 34, wherein an organic phosphorus material is used as a phosphorus source and an organic arsenic material is used as an arsenic source in the step of forming the second nitride semiconductor layer.

36. The method of claim 33, wherein the organic nitride material is asymmetric dimethylhydrazine or asymmetric dibutylhydrazine.