Wavelength selective photodetector

• US 5,726,440 A
• Filed: 11/06/1995
• Issued: 03/10/1998
• Est. Priority Date: 11/06/1995
• Status: Expired due to Fees

• Current Assignee: Methode Massachusettes, LLC
• Original Assignee: Spire Corporation
• Inventors: Kalkhoran, Nader M., Namavar, Fereydoon
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): PYO, KEVIN K
• Application Number:
  US08/553,875
• Time in Patent Office: 855 Days
• Field of Search: 250/214.1, 257/436, 257/437, 257/458, 257/464
• US Class Current: 250/214.1
• CPC Class Codes: H01L 31/103 the potential barrier being of the PN homojunction type
• CPC Class Codes: H01L 31/1812 including only AIVBIV alloys, e.g. SiGe
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A wavelength selective photodetector including: a substrate having a buried insulator layer for electrically isolating a lower section of the substrate located below the insulator layer from an upper section of the substrate located above the insulator layer; and a photon detector formed on the upper section of the substrate for detecting photons in a selected wavelength range, wherein the upper section has a selected thickness and the thickness determines at least in part the selected wavelength range of the detected photons.

Claims

1. A wavelength selective photodetector comprising:

a substrate having a buried insulator layer for electrically isolating a lower section of said substrate located below said insulator layer from an upper section of said substrate located above said insulator layer; and

photon detection means formed on said upper section of said substrate for detecting photons;

wherein said upper section has a selected thickness and said selected thickness at least in part determines a wavelength range of said photons detected by said photon detection means.

2. A wavelength selective photodetector according to claim 1 wherein said substrate comprises Si.

3. A wavelength selective photodetector according to claim 1 wherein said buried insulator layer comprises at least one of silicon oxide, silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

4. A wavelength selective photodetector according to claim 3 wherein said buried insulator layer has a thickness between about 500 Å

and about 1 micron.

5. A wavelength selective photodetector according to claim 1 wherein said upper section comprises a material having a characteristic energy band gap and said energy band gap at least in part determines said wavelength range of said photons detected by said photon detection means.

6. A wavelength selective photodetector according to claim 1 wherein said upper section comprises Si.

7. A wavelength selective photodetector according to claim 6 wherein said upper section has a thickness of less than about 2000 Å

and said selected wavelength is in a range between about 200 nm and about 400 nm.

8. A wavelength selective photodetector according to claim 6 wherein said upper section has a thickness in a range between about 500 Å

and about 1000 Å

.

9. A wavelength selective photodetector according to claim 6 wherein said upper section includes a first-type doped upper region and a second-type doped lower region and said photodetection means comprises a photodiode formed from a semiconductor junction between said upper region and said lower region.

10. A wavelength selective photodetector according to claim 9 wherein said upper region is n-type doped and said lower region is p-type doped.

11. A wavelength selective photodetector according to claim 9 wherein said upper region is p-type doped and said lower region is n-type doped.

12. A wavelength selective photodetector according to claim 9 wherein said p-type dopant is boron.

13. A wavelength selective photodetector according to claim 9 wherein said n-type dopant is As.

14. A wavelength selective photodetector according to claim 9 wherein said lower region is doped to have a dopant concentration in a range between about 1×

10¹⁵ /cm³ and about 1×

10¹⁸ /cm³.

15. A wavelength selective photodetector according to claim 9 wherein said upper region is doped to have a dopant concentration in the range between about 1×

10¹⁷ /cm³ and about 1×

10²⁰ /cm³.

16. A wavelength selective photodetector according to claim 9 further comprising:

first ohmic contact means for electrically connecting to said upper region of said semiconductor junction; and

second ohmic contact means for electrically connecting to said lower region of said semiconductor junction.

17. A wavelength selective photodetector according to claim 1 further comprising anti-reflection means formed on said photon detection means for reducing reflection loss at selected wavelengths.

18. A wavelength selective photodetector according to claim 17 wherein said anti-reflection means comprises a coating fabricated from an antireflective material.

19. A wavelength selective photodetector according to claim 18 wherein said anti-reflective material comprises at least one of SiO₂, ZnS, Si₃ N₄, MgF, TiO₂, Ta₂ O₅, and SiC.

20. A wavelength selective photodetector according to claim 17 wherein said anti-reflection means comprises a first coating of an anti-reflective material formed on said photon detection means and a second coating of a second anti-reflective material formed on said first coating.

21. A wavelength selective photodetector according to claim 20 wherein said first anti-reflective material is Si₃ N₄ and said second anti-reflective material is SiO₂.

22. A wavelength selective photodetector according to claim 1 wherein said upper section comprises SiC.

23. A wavelength selective photodetector according to claim 22 wherein said upper section has a thickness of less than about 1 micron.

24. A wavelength selective photodetector according to claim 22 wherein said upper section has a thickness in a range between about 500 Å

and about 5000 Å

.

25. A wavelength selective photodetector according to claim 22 wherein said upper section includes a first-type doped upper region and a second-type doped lower region and said photodetection means comprises a photodiode formed from a semiconductor junction between said upper region and said lower region.

26. A wavelength selective photodetector according to claim 25 wherein said upper region is p-type doped and said lower region is n-type doped.

27. A wavelength selective photodetector according to claim 25 wherein said upper region is n-type doped and said lower region is p-type doped.

28. A wavelength selective photodetector according to claim 25 wherein said p-type dopant is one of aluminum and boron.

29. A wavelength selective photodetector according to claim 25 wherein said n-type dopant is one of nitrogen and phosphorous.

30. A wavelength selective photodetector according to claim 25 wherein said upper region is doped to have a dopant concentration in a range between about 1×

10¹⁷ /cm³ and about 1×

10²⁰ /cm³.

31. A wavelength selective photodetector according to claim 25 wherein said lower region is doped to have a dopant concentration in the range between about 1×

10¹⁵ /cm³ and about 1×

10¹⁸ /cm³.

32. A wavelength selective photodetector according to claim 25 further comprising:

first ohmic contact means for electrically connecting to said upper region of said semiconductor junction; and

second ohmic contact means for electrically connecting to said lower region of said semiconductor junction.

33. A wavelength selective photodetector according to claim 1 wherein said upper section comprises a first layer and a second layer, said first layer being formed from Si and being located adjacent to said buried insulator layer and said second layer being formed from SiC and being formed on said first layer.

34. A wavelength selective photodetector according to claim 33 wherein said first layer has a thickness of between about 100 Å

and about 2000 Å

.

35. A wavelength selective photodetector according to claim 33 wherein said second layer has a thickness of between about 250 Å

and about 3000 Å

.

36. A wavelength selective photodetector according to claim 33 wherein said second layer includes a first-type doped upper region and a second-type doped lower region and said photodetection means comprises a photodiode formed from a semiconductor junction between said upper region and said lower region.

37. A wavelength selective photodetector according to claim 36 wherein said upper region is p-type doped and said lower region is n-type doped.

38. A wavelength selective photodetector according to claim 36 wherein said upper region is n-type doped and said lower region is p-type doped.

39. A wavelength selective photodetector according to claim 36 wherein said p-type dopant is one of aluminum and boron.

40. A wavelength selective photodetector according to claim 34 wherein said n-type dopant is one of nitrogen and phosphorous.

41. A wavelength selective photodetector according to claim 34 wherein said upper region is doped to have a dopant concentration in a range between about 1×

10¹⁷ /cm³ and about 1×

10²⁰ /cm³.

42. A wavelength selective photodetector according to claim 34 wherein said lower region is doped to have a dopant concentration in the range of between about 1×

10¹⁵ /cm³ and about 1×

10¹⁸ /cm³.

43. A wavelength selective photodetector according to claim 36 further comprising:

first ohmic contact means for electrically connecting to said upper region of said semiconductor junction; and

second ohmic contact means for electrically connecting to said lower region of said semiconductor junction.

44. A wavelength selective photodetector according to claim 33 wherein said first layer is doped with a first-type dopant and said second layer is doped with a second-type dopant, said first-type dopant being opposite to said second-type dopant and said photodetection means comprising a photodiode formed by a semiconductor junction between said first layer and said second layer.

45. A wavelength selective photodetector according to claim 44 further comprising:

first ohmic contact means for electrically connecting to said first-type region of said semiconductor junction; and

second ohmic contact means for electrically connecting to said second-type region of said semiconductor junction.

46. A wavelength selective photodetector comprising:

a Si-based substrate having a buried silicon oxide insulator layer for electrically isolating a lower section of said substrate located below said insulator layer from an upper section of said substrate located above said insulator layer, said upper section having a thickness of between about 500 Å and

about 1 micron, and comprising SiC;

a photodiode formed on said upper section for detecting photons within a selected wavelength range and generating an electrical signal indicative of said detection;

ohmic contacts for electrical connection to said photodiode; and

an antireflective coating formed on said photodiode for minimizing reflectance losses in said selected wavelength range.

47. A wavelength selective photodetector comprising:

a Si-based substrate having a buried silicon oxide insulator layer for electrically isolating a lower section of said substrate located below said insulator layer from an upper section of said substrate located above said insulator layer, said upper section having a first layer and a second layer, said first layer being formed from Si and being located adjacent to said buried insulator layer and said second layer being formed from SiC and being formed on said first layer;

a photodiode formed on said upper section for detecting photons within a selected wavelength range and generating an electrical signal indicative of said detection;

ohmic contacts for electrical connection to said photodiode; and

an antireflective coating formed on said photodiode for minimizing reflectance losses in said selected wavelength range.