Claims
- 1. An intersubband optical device comprising
first quantum well interior regions having upper and lower energy states between which intersubband transitions take place; and superlattice barrier regions interposed between said first quantum well interior regions so as to produce upper and lower minibands of energy levels, said superlattice barrier regions including second barrier regions and second quantum well interior regions, said second quantum well interior regions being interposed between said second barrier regions, said first quantum well interior regions and said super lattice barrier regions being configured to produce an energy gap between said upper and lower states that is larger than the energy of an approximately 1.7 μm wavelength photon.
- 2. The invention of claim 1 wherein said second quantum well interior regions are narrower than said first quantum well interior regions.
- 3. The invention of claim 2 wherein said first quantum well interior regions are at least 1.5 times as wide as said second quantum well interior regions.
- 4. The invention of claim 2 wherein said one of said first and second quantum well interior regions comprises GaN.
- 5. The invention of claim 2 wherein said barrier regions comprise a compound of AlxGa1−xN.
- 6. The invention of claim 5 wherein x is less than about 0.85.
- 7. The invention of claim 5 wherein x is less than about 0.70.
- 8. The invention of claim 5 wherein said first quantum well interior regions are least 2 times as wide as said second quantum well interior regions.
- 9. The invention of claim 2 wherein said first quantum well interior regions and said superlattice barrier regions are configured to position a Fermi level below said lower miniband of said superlattice barrier regions and above said lower energy state of said first quantum well interior regions.
- 10. The invention of claim 2 wherein said first quantum well interior regions are doped with an n-type impurity to a concentration of about 0.1-10×1020 cm−3.
- 11. The invention of claim 2 wherein said second quantum well interior regions are doped with an n-type impurity to a concentration of about 0.1-10×1020 cm−3.
- 12. The invention of claim 2 wherein said quantum well regions comprise a compound of InxGa1−xN.
- 13. An electro-optical apparatus comprising
a semiconductor body having a stacked, multilayered construction, said body including first quantum well interior regions having upper and lower energy states between which intersubband transitions take place, and superlattice barrier regions interposed between said first quantum well interior regions so as to produce upper and lower minibands of energy levels within said superlattice barrier regions, said superlattice barrier regions including second barrier regions and second quantum well interior regions, said second quantum well interior regions being interposed between said second barrier regions, said first quantum well interior regions and said super lattice barrier regions being configured to produce an energy gap between said upper and lower states that is larger than the energy of an approximately 1.7 μm wavelength photon, and means for applying and/or extracting energy from said body.
- 14. The invention of claim 13 wherein said applying and/or extracting means comprises ohmic contacts electrically coupled to said body.
- 15. The invention of claim 13 wherein said applying means includes means for optically pumping said body.
- 16. An intersubband optical device comprising
a core region including a multiplicity of repeat units, each of said repeat units including a first barrier region and a quantum well active region disposed adjacent thereto, characterized in that each of said quantum well active regions has upper and lower energy states separated by an energy greater than the energy of a 1.7 μm photon, and said barrier region comprises a superlattice configured to have minibands separated by minigaps that confine electrons to said upper state.
- 17. The invention of claim 16 wherein each said superlattice comprises a multiplicity of second quantum well regions and second barrier regions interleaved with one another, and at a least one of said second quantum well regions is doped such that electrons are transported from said at least one second quantum well region into an active quantum well region.
- 18. The invention of claim 17 wherein said active region quantum wells comprise GaN, said second quantum well regions comprise AlyGa1−yN and said second barrier regions comprise AlxGa1−xN.
- 19. The invention of claim 18 wherein 0≦y≦0.2 and x>0.65 approximately.
- 20. The invention of claim 18 wherein said quantum well active regions and said second barrier regions are essentially undoped and said second quantum well regions are doped n-type.
- 21. The invention of claim 18 further including a substrate on which said core region is formed and a transition zone disposed between said substrate and said core region, said transition zone including a buffer region disposed on said substrate and a template region disposed on said buffer region, thereby to redistribute charge accumulated at the interfaces between said quantum well active regions and said first barrier regions so as to increase the built-in electric field in said quantum well active regions and to decrease the built-in electric field in said second barrier regions.
- 22. The invention of claim 21 wherein said buffer region comprises relatively thin, high-temperature AlN, said template region comprises relatively thick, high-temperature GaN or AlzGa1−zN, and at least two separated, relatively thinner, low-temperature AlN layers embedded in said template region.
- 23. The invention of any one of claims 16-22 further including means for absorbing in said core region an optical photon having a wavelength shorter than about 1.7 μm so as to generate a photocurrent, and means for utilizing said photocurrent.
- 24. The invention of any one of claims 16-22 further including means for applying pump energy to said core region, thereby to cause said actives to emit optical photons having a wavelength shorter than about 1.7 μm, and means for utilizing said photons.
- 25. The invention of claim 16 wherein said quantum well active regions and said first barrier regions are configured to position a Fermi level below said lower miniband of said first barrier regions and above said lower energy state of said active well interior regions.
- 26. The invention of claim 16 wherein said quantum well active regions comprise a compound of InxGa1−xN.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from provisional application Serial No. 60/249,078 entitled Quantum Well Stacks that Absorb at Wavelengths Shorter than 1.7 μm filed on Nov. 15, 2000 and provisional application Serial No. 60/313,403 entitled Optical Devices with Heavily Doped and Coupled Quantum Wells (Cho-Gmachl-Ng 108-22-4) filed on Aug. 17, 2001.
Provisional Applications (2)
|
Number |
Date |
Country |
|
60249078 |
Nov 2000 |
US |
|
60313403 |
Aug 2001 |
US |