Guided-wave photodiode using through-absorber quantum-well-intermixing and methods thereof
The present invention includes a high-speed, high-saturation power detector (e.g., a photodiode) compatible with a relatively simple monolithic integration process. In particular embodiments, the photodiode includes an intrinsic bulk absorption region, which is grown above a main waveguide core including a number of quantum wells (QWs) that are used as the active region of a phase modulator. The invention also includes methods of fabricating integrated photodiode and waveguide assemblies using a monolithic, simplified process.
1. A method of fabricating an integrated structure, the method comprising:
providing a base structure comprising a multiple-quantum-well (MQW) region and a photodiode region;
patterning a top surface of the base structure with a mask to define an active region and a passive region;
introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region, thereby producing an intermixed MQW region; and
depositing one or more cladding layers on the photodiode region.
2. The method of claim 1 , wherein the base structure comprises the MQW region underlying the photodiode region.
3. The method of claim 2 , wherein the base structure further comprises an implant layer disposed above the photodiode region.
4. The method of claim 3 , wherein the MQW region is disposed between two confinement layers.
5. The method of claim 1 , wherein the photodiode region comprises an absorption region, an electron drift region, and/or a sub-collector region.
6. The method of claim 5 , wherein the base structure further comprises a waveguide region disposed beneath the photodiode region, wherein the waveguide region comprises the MQW region.
7. The method of claim 6 , wherein the base structure further comprises a field termination layer disposed between the photodiode region and the waveguide region.
8. The method of claim 7 , wherein the base structure further comprises an n-type cladding layer and/or an n-type contact layer disposed beneath the MQW region.
9. The method of claim 8 , wherein the base structure further comprises one or more bandgap grade layers between two layers having a different bandgap separation.
10. The method of claim 1 , further comprising removing the mask.
11. The method of claim 1 , wherein the introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region comprises implanting an ion into the base structure, thereby creating an implanted structure, and annealing the implanted structure, thereby diffusing one or more vacancies through the photodiode region and into the MQW region and producing the intermixed MQW region.
12. The method of claim 1 , further comprising patterning a top surface of the base structure with a photodiode mask to define a photodiode, wherein the photodiode comprises a portion of the photodiode region.
13. The method of claim 12 , further comprising removing a portion of the base structure, thereby releasing the photodiode from the base structure.
14. The method of claim 1 , further comprising, after step iii), depositing one or more contact layers on the one or more cladding layers.
15. A method of fabricating an integrated structure, the method comprising:
providing a base structure comprising a multiple-quantum-well (MQW) region and a photodiode region;
patterning a top surface of the base structure with a hard mask to define an active region and a passive region;
introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region, thereby producing an intermixed MQW region within the active region;
removing the hard mask, thereby exposing a top surface of the base structure having the intermixed MQW region;
patterning a top surface of the base structure with a photodiode mask to define a photodiode, wherein the photodiode comprises a portion of the photodiode region; and
removing a portion of the base structure, thereby releasing the photodiode from the base structure.
16. The method of claim 15 , further comprising depositing one or more cladding layers on the photodiode region, thereby providing a cladded base structure.
17. The method of claim 16 , further comprising depositing and/or patterning one or more contact layers on a top surface or a bottom surface of the cladded base structure.
18. The method of claim 15 , wherein the introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region comprises implanting an ion into the base structure, thereby creating an implanted structure, and annealing the implanted structure, thereby diffusing one or more vacancies through the photodiode region and into the MQW region and producing the intermixed MQW region.
19. A method of fabricating an integrated structure, the method comprising:
providing a base structure comprising a multiple-quantum-well (MQW) region and a photodiode region;
patterning a top surface of the base structure with a hard mask to define an active region and a passive region;
introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region;
removing the hard mask, thereby exposing a top surface of the base structure having the intermixed MQW region;
patterning a top surface of the base structure with a photodiode mask to define a photodiode, wherein the photodiode comprises a portion of the photodiode region;
removing a portion of the base structure; and
depositing one or more cladding layers on the photodiode region, thereby providing a cladded base structure.
20. The method of claim 19 , further comprising depositing one or more contact layers on a top surface or a bottom surface of the cladded base structure.
21. The method of claim 19 , wherein the introducing impurities, creating vacancies, or heating through the photodiode region and into the MQW region comprises implanting an ion into the base structure, thereby creating an implanted structure, and annealing the implanted structure, thereby diffusing one or more vacancies through the photodiode region and into the MQW region and producing the intermixed MQW region.
22. The method of claim 19 , wherein the MQW region is between two confinement layers.