Nitride semiconductor laser element and optical device containing it
A nitride semiconductor light emitting device includes a processed substrate ( 101 a ) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer ( 102 ) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer ( 106 ) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer ( 103-105 ) and a p type layer ( 107-110 ) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 μm away from the center of the groove in the width direction and more than 1 μm away from the center of the hill in the width direction.
1. A nitride semiconductor laser device, comprising:
a processed substrate ( 101 a ) including a groove and a hill formed on a main surface of a nitride semiconductor substrate;
a nitride semiconductor underlayer ( 102 ) covering the groove and the hill of said processed substrate; and
a light emitting device structure having a light emitting layer ( 106 ) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer ( 103 - 105 ) and a p type layer ( 107 - 110 ) over said nitride semiconductor underlayer,
a current-constricting portion (RS) of said light emitting device structure being formed above a region more than 1 μm away from the center of said groove in the width direction and more than 1 μm away from the center of said hill in the width direction.
2. The nitride semiconductor laser device according to claim 1 , wherein said current-constricting portion is formed above a region more than 1 μm away from the center of said groove in the width direction and within the width of said groove.
3. The nitride semiconductor laser device according to claim 1 , wherein said current-constricting portion is formed above a region more than 1 μm away from the center of said groove in the width direction and across the groove and the hill.
4. The nitride semiconductor laser device according to claim 1 , wherein at least either of the width of said groove and the width of said hill is in a range of 4-30 μm.
5. The nitride semiconductor laser device according to claim 1 , wherein the width of said groove is wider than the width of said hill.
6. The nitride semiconductor laser device according to claim 1 , wherein said groove has a depth in a range of 1-10 μm.
7. The nitride semiconductor laser device according to claim 1 , wherein said nitride semiconductor underlayer is formed of GaN containing at least one impurity selected from Si, O, Cl, S, C, Ge, Zn, Cd, Mg and Be in a range from 1×10 17 /cm 3 to 5×10 18 /cm 3 .
8. The nitride semiconductor laser device according to claim 1 , wherein said nitride semiconductor underlayer includes Al x Ga 1-x N (0.01≦x≦0.15).
9. The nitride semiconductor laser device according to claim 1 , wherein said nitride semiconductor underlayer includes In x Ga 1-x N (0.01≦x≦0.18).
10. The nitride semiconductor laser device according to claim 1 , wherein said quantum well layer contains at least one of As, P and Sb.
11. A nitride semiconductor laser device, comprising:
a mask substrate ( 101 m ) including a mask pattern formed on a main surface of a nitride semiconductor substrate,
said mask pattern including a plurality of stripe masks ( 200 ) and a plurality of stripe windows arranged alternately, each said mask being formed of a growth inhibiting film for suppressing epitaxial growth of a nitride semiconductor layer thereon, and each said window being unprovided with said growth inhibiting film;
a nitride semiconductor underlayer ( 102 ) covering said mask pattern; and
a light emitting device structure having a light emitting layer ( 106 ) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer ( 103 - 105 ) and a p type layer ( 107 - 110 ) over the underlayer,
a current-constricting portion (RS) through which substantial electric current is introduced into said light emitting device structure being formed above a region more than 1 μm away from the center of said mask in the width direction and more than 1 μm away from the center of said window in the width direction.
12. The nitride semiconductor laser device according to claim 11 , wherein said current-constricting portion is formed above a region more than 1 μm away from the center of said mask in the width direction and within a width of said mask.
13. The nitride semiconductor laser device according to claim 11 , wherein said current-constricting portion is formed above a region across said mask and said window.
14. The nitride semiconductor laser device according to claim 11 , wherein said mask has a width of more than 5 μm and less than 30 μm.
15. The nitride semiconductor laser device according to claim 11 , wherein said window has a width of more than 2 μm and less than 20 μm.
16. The nitride semiconductor laser device according to claim 11 , wherein the width of said mask is wider than the width of said window.
17. The nitride semiconductor laser device according to claim 11 , wherein said nitride semiconductor underlayer includes Al x Ga 1-x N (0.01≦x≦0.15).
18. The nitride semiconductor laser device according to claim 11 , wherein said nitride semiconductor underlayer includes In x Ga 1-x N (0.01≦x≦0.18).
19. The nitride semiconductor laser device according to claim 11 , wherein said quantum well layer contains at least one of As, P and Sb.
20. The nitride semiconductor laser device according to claim 11 , wherein said nitride semiconductor substrate contains at least one impurity selected from Si, O, Cl, S, C, Ge, Zn, Cd, Mg and Be in a concentration range of more than 5×10 17 /cm 3 and less than 5×10 18 /cm 3 .
21. The nitride semiconductor laser device according to claim 1 , wherein said nitride semiconductor substrate is made of GaN or AlGaN.
22. The nitride semiconductor laser device according to claim 1 , wherein said nitride semiconductor substrate has an n type conductivity and then an n electrode including Hf is provided on the other main surface of said nitride semiconductor substrate.
23. The nitride semiconductor laser device according to claim 1 , wherein a p electrode including at least one element of Pd, Pt and Mo is provided on said p type layer.
24. The nitride semiconductor laser device according to claim 1 , wherein said p type layer includes a GaN contact layer containing Mg as a p type impurity and then a p electrode is provided on said GaN contact layer and wherein concentration of Mg in said GaN contact layer is increased as approaching the interface with said p electrode.
25. The nitride semiconductor laser device according to claim 11 , wherein said nitride semiconductor substrate is made of GaN or AlGaN.
26. The nitride semiconductor laser device according to claim 11 , wherein said nitride semiconductor substrate has an n type conductivity and then an n electrode including Hf is provided on the other main surface of said nitride semiconductor substrate.
27. The nitride semiconductor laser device according to claim 11 , wherein a p electrode including at least one element of Pd, Pt and Mo is provided on said p type layer.
28. The nitride semiconductor laser device according to claim 11 , wherein said p type laser includes a GaN contact layer containing Mg as a p type impurity and then a p electrode is provided on said GaN contact layer and wherein concentration of Mg in said GaN contact layer is increased as approaching the interface with said p electrode.