Tensile strained semiconductor photon emission and detection devices and integrated photonics system
Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.
1. An optical device comprising a wafer having a germanium region, the germanium region in contact with and surrounded by a single tensile stressor region within a plane of the wafer, the single tensile stressor region inducing biaxial tensile strain within at least a portion of the germanium region in the plane of the wafer, the biaxial tensile strain causing at least a portion of the germanium region to have a reduced band gap from that which would exist in the germanium region absent the presence of the tensile stressor region.
2. The optical device of claim 1 wherein the biaxial tensile strain induced in the portion of the germanium region is sufficient to cause the portion of the germanium region to have a direct band gap.
3. The optical device of claim 1 wherein a junction is located adjacent the portion of the germanium region, the junction having a first side with a first majority carrier type and a second side with a second majority carrier type; and the optical device further comprises first and second contacts coupled respectively to the first side of the junction and the second side of the junction.
4. The optical device of claim 1 wherein the tensile stressor region comprises epitaxial silicon germanium.
5. The optical device of claim 1 , wherein the tensile stressor region comprises silicon nitride.
6. The optical device of claim 1 , wherein optical element is included in an optical path through a plurality of germanium regions in the wafer.
7. The optical device of claim 6 , wherein the optical path includes a first mirror and a second mirror that define a laser cavity.
8. The optical device of claim 7 , wherein the first mirror and the second mirror are distributed Bragg reflectors and wherein the laser cavity incorporates the plurality of germanium regions.
9. The optical device of claim 8 , wherein the laser cavity is disposed at least partially within a waveguide.
10. The optical device of claim 9 , wherein the waveguide is a germanium waveguide.
11. The optical device of claim 9 , wherein the waveguide comprises one of silicon, silicon oxide, or silicon nitride.
12. The optical device of claim 1 , wherein the optical device is adjacent a laser cavity and wherein the laser cavity is coupled to a plurality of germanium regions in the wafer through evanescent coupling.
13. The optical device of claim 12 , wherein the laser cavity is defined by a first mirror and a second mirror formed on end faces of the laser cavity.
14. The optical device of claim 12 , wherein the laser cavity is defined by a first distributed Bragg reflector and a second distributed Bragg reflector.
15. The optical device of claim 12 , wherein the laser cavity is defined by a first distributed Bragg reflector and a second distributed Bragg reflector.
16. The optical device of claim 14 , wherein the waveguide comprises one of a germanium, silicon, silicon germanium, silicon oxide, or silicon nitride waveguide.
17. The optical device of claim 7 , wherein the first mirror and the second mirror are formed on end faces of the laser cavity and wherein the laser cavity incorporates the plurality of germanium regions.
18. The optical device of claim 17 , wherein the laser cavity is out-coupled to other optical elements.
19. The optical device of claim 18 , wherein the other optical elements are one or more of: waveguides, couplers, detectors, mirrors, optical modulators, beam splitters, and combinations of the foregoing.
20. The optical device of claim 13 , wherein the laser cavity comprises one of silicon, silicon germanium, silicon oxide, or silicon nitride.