Nitride semiconductor laser element and method for manufacturing the same

Abstract

A nitride semiconductor laser element, has: a nitride semiconductor layer comprising a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer laminated in that order; and resonator end faces formed mutually opposing at the end of said nitride semiconductor layers, wherein an impurity is contained in at least an optical output region of the resonator end faces, with the concentration of said impurity having a concentration distribution that is asymmetric in reference to a peak position, in the lamination direction of the nitride semiconductor layers, and said optical output region has a wider bandgap than other regions in the active layer or said optical output region has a higher impurity concentration than other regions in the active layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1b comprise simplified cross sections of the main components, for illustrating the structure of the nitride semiconductor laser element of the present invention;

FIG. 2 a to 2d comprise simplified plan views illustrating the position of the region where ions are implanted in the nitride semiconductor laser element of the present invention;

FIGS. 3 a and 3b comprises simplified cross sections illustrating the position of the region where ions are implanted at the resonator end faces in the nitride semiconductor laser element of the present invention;

FIGS. 4 a to 4e and 4c′ to 4e′ are simplified cross sections illustrating the method for manufacturing a nitride semiconductor laser element of the present invention;

FIGS. 5 a to 5c are simplified cross sections illustrating the method for manufacturing a nitride semiconductor laser element of the present invention;

FIGS. 6 a to 6c are simplified cross sections illustrating the method for manufacturing a nitride semiconductor laser element of the present invention;

FIG. 7 is a graph illustrating the optical transmissivity of the semiconductor layer in the nitride semiconductor laser element of the present invention;

FIG. 8 is a graph of the impurity profile of the semiconductor layer of the nitride semiconductor laser element of the present invention; and

FIGS. 9 a and 9b are simplified cross sectional process diagrams illustrating a conventional method for manufacturing a nitride semiconductor laser element.

Claims

1. A nitride semiconductor laser element, having: a nitride semiconductor layer comprising a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer laminated in that order; andresonator end faces formed mutually opposing at the end of said nitride semiconductor layers,wherein an impurity is contained in at least an optical output region of the resonator end faces, with the concentration of said impurity having a concentration distribution that is asymmetric in reference to a peak position, in the lamination direction of the nitride semiconductor layers, andsaid optical output region has a wider bandgap than other regions in the active layer.

2. A nitride semiconductor laser element, having: a nitride semiconductor layer comprising a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer laminated in that order; andresonator end faces formed mutually opposing at the end of said nitride semiconductor layers,wherein an impurity is contained in at least an optical output region of the resonator end faces, with the concentration of said impurity having a concentration distribution that is asymmetric in reference to a peak position, in the lamination direction of the nitride semiconductor layers, andsaid optical output region has a higher impurity concentration than other regions in the active layer.

3. The nitride semiconductor laser element according to claim 1, wherein the impurity concentration is higher on the first nitride semiconductor layer side than on the second nitride semiconductor layer side.

4. The nitride semiconductor laser element according to claim 1, wherein the impurity concentration has a higher attenuation rate at the resonator end faces to the second nitride semiconductor layer side, using the peak position as a reference, than the attenuation rate to the first nitride semiconductor layer side.

5. The nitride semiconductor laser element according to claim 1, wherein the other regions on the active layer is regions on both sides of the optical output region on the resonator end faces.

6. The nitride semiconductor laser element according to claim 1, wherein the portion containing an impurity on the resonator end faces is in the form of an inverted triangle or of a top hat shape that is convex downward.

7. The nitride semiconductor laser element according to claim 1, wherein the portion containing an impurity on the resonator end faces is wider than the inner side of the element on the resonator end face side.

8. The nitride semiconductor laser element according to claim 1, wherein the impurity includes at least one atom selected from the group consisting of oxygen, boron, aluminum, zinc, beryllium, carbon, magnesium, calcium and nitrogen.

9. The nitride semiconductor laser element according to claim 1, wherein the impurity is introduced by ion implantation.

10. The nitride semiconductor laser element according to claim 1, wherein there is a stripe-like ridge on the surface of the second nitride semiconductor layer.

11. A method for manufacturing a nitride semiconductor laser element, comprising the steps of: (a) forming a nitride semiconductor layer including at least a first nitride semiconductor layer and an active layer;(b) forming over said active layer a protective layer having a first region and a second region that is thicker than the first region;(c) implanting an ion species in the nitride semiconductor layer via the protective layer so that the ions reach the active layer through the protective layer in the first region of the protective layer;(d) exposing the nitride semiconductor layer by removing the protective layer;(e) forming a second nitride semiconductor layer over said nitride semiconductor layer; and(f) dividing the nitride semiconductor layer so that the portion where the ion species is implanted to be the resonator end face on the optical output side.

12. The method according to claim 11, wherein the second nitride semiconductor layer is formed with a laminated structure, at least one layer of the second nitride semiconductor layer is formed over the active layer in step (a), and the remaining second nitride semiconductor layers are formed in step (e).

13. The method according to claim 11, wherein the first region of a protective film has a thickness that varies in steps or as a slope.

14. The method according to claim 11, wherein the first region of a protective film is thinnest in the middle part.

15. The method according to claim 11, wherein the portion containing an impurity on the resonator end faces is in the form of an inverted triangle or of a top hat shape that is convex downward.

16. The method according to claim 11, further comprising a step of performing a heat treatment after step (c).

17. The method according to claim 11 wherein, in step (c), an ion species is implanted in at least the portion that serves as the optical output region of the optical output end face of the laser element.

18. The method according to claim 11, wherein, in step (c), the impurity includes at least one atom selected from the group consisting of oxygen, boron, aluminum, zinc, beryllium, carbon, magnesium, calcium and nitrogen.

19. The method according to claim 11, wherein, after step (e), the bandgap of the portion of the active layer where the ion species is implanted is different from the bandgap of other regions of the active layer.

20. The method according to claim 11, wherein, after step (e), the composition of the portion of the active layer where the ion species is implanted is different from the composition of other regions of the active layer.

21. The method according claim 11, wherein, after step (f), the optical transmissivity of the portion of the active layer where the ion species is implanted is at least 100% with respect to the active layer prior to the implantation of the ion species.

22. The nitride semiconductor laser element according to claim 2, wherein the impurity concentration is higher on the first nitride semiconductor layer side than on the second nitride semiconductor layer side.

23. The nitride semiconductor laser element according to claim 2, wherein the impurity concentration has a higher attenuation rate at the resonator end faces to the second nitride semiconductor layer side, using the peak position as a reference, than the attenuation rate to the first nitride semiconductor layer side.

24. The nitride semiconductor laser element according to claim 2, wherein the other regions on the active layer is regions on both sides of the optical output region on the resonator end faces.

25. The nitride semiconductor laser element according to claim 2, wherein the portion containing an impurity on the resonator end faces is in the form of an inverted triangle or of a top hat shape that is convex downward.

26. The nitride semiconductor laser element according to claim 2, wherein the portion containing an impurity on the resonator end faces is wider than the inner side of the element on the resonator end face side.

27. The nitride semiconductor laser element according to claim 2, wherein the impurity includes at least one atom selected from the group consisting of oxygen, boron, aluminum, zinc, beryllium, carbon, magnesium, calcium and nitrogen.

28. The nitride semiconductor laser element according to claim 2, wherein the impurity is introduced by ion implantation.

29. The nitride semiconductor laser element according to claim 2, wherein there is a stripe-like ridge on the surface of the second nitride semiconductor layer.