Migration enhanced epitaxy fabrication of active regions having quantum wells
View Patent ↗Semiconductor lasers, such as VCSELs having active regions with flattening layers associated with nitrogen-containing quantum wells are disclosed. MEE (Migration Enhanced Epitaxy) is used to form a flattening layer upon which a quantum well is formed and thereby enhance smoothness of quantum well interfaces and to achieve narrowing of the spectrum of light emitted from nitrogen containing quantum wells. A cap layer is also formed over the quantum well.
1. An active region associated with a semiconductor laser, comprising:
a first flattening layer comprising a first section having from about 7 to about 73 alternating monolayers of group III and group V elements;
a nitrogen containing quantum well formed on the flattening layer, wherein the flattening layer is grown with a flux of group V elements and the quantum well is grown with a higher flux of group V elements than at least a portion of the monolayers of the flattening layer; and
a cap layer formed on the quantum well;
a plurality of additional quantum wells, wherein each quantum well has a flattening layer on a first surface thereof and a cap layer on a second surface thereof.
2. An active region as defined in claim 1 , wherein the flattening layer is substantially nitrogen free.
3. An active region as defined in claim 1 , wherein the cap layer comprises GaAs.
4. An active region as defined in claim 1 , wherein the cap layer comprises GaAsN.
5. An active region as defined in claim 1 , wherein the quantum well comprises InGaAsN.
6. An active region as defined in 1 , wherein the quantum well comprises InGaAsNSb.
7. An active region as defined in claim 1 , wherein the quantum well comprises InGaAsN.
8. A VCSEL comprising an active region as defined in claim 1 .
9. A VCSEL as defined in claim 8 , further comprising:
a GaAs substrate; a GaAs/AlGaAs lower Bragg reflector formed on the substrate;
a lower cladding layer formed on the lower Bragg reflector;
the active region as defined in claim 1 formed on the lower cladding region, wherein the group III constituent comprises Ga and the group V constituent comprises As;
an upper cladding layer formed on the active region; and
a GaAs upper Bragg reflector formed on the upper cladding layer.
10. An active region associated with a semiconductor laser, comprising:
a plurality of nitrogen containing quantum wells, each quantum well having a flattening layer on a first surface thereof and a cap layer on a second surface thereof,
the flattening layer comprising a first section having from about 7 to about 73 alternating monolayers of group III and group V elements; and
the quantum well comprising InGaAsN and being formed on the flattening layer, wherein the flattening layer is grown with a flux of group V elements and the quantum well is grown with a higher flux of group V elements than at least a portion of the monolayers of the flattening layer.
11. An active region as defined in claim 10 , wherein the flattening layer is substantially nitrogen free.
12. An active region as defined in claim 10 , wherein the cap layer comprises GaAs.
13. An active region as defined in claim 10 , wherein the cap layer comprises GaAsN.
14. An active region as defined in claim 10 , wherein the quantum well comprises InGaAsN.
15. An active region as defined in 10 , wherein the quantum well comprises InGaAsNSb.
16. A VCSEL comprising an active region as defined in claim 10 .
17. A VCSEL as defined in claim 16 , further comprising:
a GaAs substrate;
a GaAs/AlGaAs lower Bragg reflector formed on the substrate;
a lower cladding layer formed on the lower Bragg reflector;
the active region as defined in claim 11 formed on the lower cladding region, wherein the group III constituent comprises Ga and the group V constituent comprises As;
an upper cladding layer formed on the active region; and
a GaAs upper Bragg reflector formed on the upper cladding layer.