Surface-emitting semiconductor laser
View Patent ↗The invention relates to a semiconductor laser of the surface emitting type. In order to provide a semiconductor laser which can be operated at normal ambient temperatures and has stable long-term characteristics, the semiconductor laser comprises an active zone having a pn transition, a first n-doped semiconductor layer on the n side of the active zone, a structured tunnel contact on the p side of the active zone, which forms a conductive transition to a second n-doped semiconductor layer on the p-side of the active zone, a structured dielectric mirror, which is applied to the second n-doped semiconductor layer, a contact layer, which forms a contact with the second n-doped semiconductor layer at the places where the dielectric mirror is not applied, and a diffusion barrier between the contact layer and the second n-doped semiconductor layer.
1. A semiconductor laser of the surface emitting type, comprising:
an active zone having a pn transition;
a first n-doped semiconductor layer on an n side of the active zone,
a structured tunnel contact on a p side of the active zone which forms a conductive transition to a second n-doped semiconductor layer on the p side of the active zone;
a structured dielectric mirror which is applied to the second n-doped semiconductor layer;
a contact layer which forms a contact with the second n-doped semiconductor layer at points where the dielectric mirror is not applied; and
a diffusion barrier between the contact layer and the second n-doped semiconductor layer, wherein the dielectric mirror laterally partially overlaps the diffusion barrier.
2. A semiconductor laser according to claim 1 , comprising an adhesion promoter between the diffusion barrier and the second semiconductor layer.
3. A semiconductor laser according to claim 2 , the adhesion promoter comprising a layer of titanium.
4. A semiconductor laser according to claim 1 , the diffusion barrier comprising a layer of platinum.
5. A semiconductor laser according to claim 1 , further comprising a metallic covering layer between the dielectric mirror and the contact layer for increasing reflectivity.
6. A semiconductor laser according to claim 5 , the metallic covering layer located through and between the diffusion barrier and the contact layer.
7. A semiconductor laser according to claim 6 , the metallic covering layer comprising gold.
8. A semiconductor laser according to claim 1 , the contact layer comprising one of gold and silver.
9. A semiconductor laser according to claim 1 , the dielectric mirror having a lower heat resistance than semiconductor materials.
10. A semiconductor laser according to claim 1 , wherein the second n-doped semiconductor layer comprises an InP semiconductor.
11. A semiconductor laser according to claim 1 , the contact layer having sufficient thickness to act as a heat sink.
12. A semiconductor laser according to claim 11 , the contact layer being more than 10 μm thick.
13. A semiconductor laser according to claim 1 , wherein light is decoupled on the n side of the active zone.
14. A semiconductor laser according to claim 13 , further comprising a substrate removed from the n side of the active zone.
15. A semiconductor laser according to claim 14 , the contact layer having sufficient thickness to ensure mechanical stability of the semiconductor laser with the substrate removed from the n side of the active zone.
16. A process for producing a diffusion barrier in a semiconductor laser with an active zone having a pn transition, comprising:
forming a first n-doped semiconductor layer on an n side of the active zone,
forming a structured tunnel contact on a p side of the active zone which forms a conductive transition to a second n-doped semiconductor layer on the p side of the active zone,
applying a diffusion barrier to the second n-doped semiconductor layer;
applying a dielectric mirror to the second n-doped semiconductor layer such that the dielectric mirror laterally partially overlaps the diffusion barrier; and
applying a contact layer at least over the diffusion barrier.
17. A process according to claim 16 , wherein applying the dielectric mirror comprises applying the dielectric mirror before the diffusion barrier is applied.
18. A process according to claim 16 , wherein applying the dielectric mirror comprises applying the dielectric mirror after the diffusion barrier is applied.
19. A process according to claim 16 , further comprising applying an adhesion promoter before the diffusion barrier.
20. A process according to claim 19 , wherein applying the adhesion promoter comprises utilizing titanium.
21. A process according to claim 16 , the step of applying a diffusion barrier comprising utilizing platinum.
22. A process according to claim 16 , wherein applying the contact layer comprises applying a metallic contact layer over an entire surface of the diffusion barrier and the dielectric mirror.
23. A process according to claim 22 , wherein applying the metallic contact layer comprises forming the metallic contact layer from one of gold and silver.
24. A process according to claim 22 , further comprising applying a metallic covering layer before the contact layer is applied over the dielectric mirror.
25. A process according to claim 22 , further comprising applying a metallic covering layer before the contact layer is applied over the entire surface of the dielectric mirror and the diffusion barrier.
26. A process according to claim 24 , wherein applying the metallic covering layer comprises forming the metallic covering layer from gold.
27. A semiconductor laser according to claim 1 , the dielectric mirror laterally adjoining the diffusion barrier.