Patch coupled infrared photodetector

• US 5,773,831 A
• Filed: 03/19/1997
• Issued: 06/30/1998
• Est. Priority Date: 03/19/1997
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Lockheed Martin Vought Systems Corp (Martin Marietta Corporation)
• Inventors: Brouns, Austin John
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Jiron, Darren M.
• Application Number:
  US08/820,976
• Time in Patent Office: 468 Days
• Field of Search: 250/370.08, 250/332, 250/370.06, 250/338.4, 250/370.14, 257/21, 257/184, 257/436, 257/432, 257/448
• US Class Current: 250/370.08
• CPC Class Codes: G01J 5/28 using photoemissive or photovoltaic cells
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/1465 of the hybrid type

Abstract

An infrared detector element includes a metallic patch which is positioned on the surface of an upper contact layer. A multiple quantum well ("MQW") infrared sensitive structure is positioned between the first contact layer and a second contact layer. The conductive contact layers are transparent to infrared radiation. A groundplane which is reflective to infrared radiation is positioned adjacent the second contact layer. A resonant cavity is formed between the metallic patch and the groundplane. The thickness of this cavity is not greater than approximately one eighth of the wavelength of the incident infrared radiation within the cavity. The metallic patch functions to couple the incident infrared radiation into the resonant cavity wherein the E-field is oriented substantially normal to the plane of the MQW structure. A plurality of the detector elements can be used to form a single pixel and an array of the pixels can be used to form a complete infrared radiation imager.

Claims

1. An infrared radiation detector comprising:

a planar, infrared radiation sensitive structure for producing carriers in response to infrared radiation, said infrared radiation sensitive structure having first and second surfaces,

a first electrically conductive layer proximate said infrared sensitive structure first surface and electrically connected thereto, said first electrically conductive layer transparent to said infrared radiation,

a planar patch conductive for said infrared radiation positioned on the surface of said first conductive layer opposite said infrared sensitive structure, said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said infrared sensitive structure,

an electrically conductive, planar infrared radiation reflective layer positioned proximate said second surface of said infrared sensitive structure and electrically connected thereto, and

wherein a resonant cavity is formed between said conductive patch and said reflective layer, said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said infrared sensitive structure.

2. An infrared radiation detector as recited in claim 1 wherein said planar, infrared radiation sensitive structure is a multiple quantum well structure.

3. An infrared radiation detector as recited in claim 1 wherein said planar, infrared radiation sensitive structure comprises mercury cadmium telluride.

4. An infrared radiation detector as recited in claim 1 including a second electrically conductive layer positioned between and electrically connected with said infrared radiation sensitive structure and said reflective layer, said second electrically conductive layer transparent to said infrared radiation.

5. An infrared radiation detector as recited in claim 1 wherein said patch is round.

6. An infrared radiation detector as recited in claim 1 wherein said patch is square.

7. An infrared radiation detector as recited in claim 1 wherein said patch is elongate.

8. An infrared radiation detector as recited in claim 1 wherein said first electrically conductive layer and said infrared radiation sensitive structure are patterned to have a least a portion thereof shaped to have a similar configuration to said patch.

9. An infrared radiation detector as recited in claim 1 wherein said infrared sensitive structure is tuned for a maximum photoconductive response for infrared radiation having a wavelength in said infrared sensitive structure which is approximately eight times that of the thickness of said infrared sensitive structure.

10. An infrared radiation detector comprising:

a planar multiple quantum well structure for producing carriers in response to infrared radiation, said quantum well structure having first and second surfaces,

a first electrically conductive layer located on said quantum well structure first surface, said first electrically conductive layer transparent to said infrared radiation,

a second electrically conductive layer located on said quantum well structure second surface, said second electrically conductive layer transparent to said infrared radiation,

a planar patch conductive for said infrared radiation positioned on the surface of said first conductive layer opposite said multiple quantum well structure, said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said quantum well structure,

an electrically conductive, planar infrared radiation reflective layer positioned on the surface of said second conductive layer opposite said multiple quantum well structure, and

wherein a resonant cavity is formed between said conductive patch and said reflective layer, said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said quantum well structure.

11. An infrared radiation detector as recited in claim 10 wherein said patch is round.

12. An infrared radiation detector as recited in claim 10 wherein said patch is square.

13. An infrared radiation detector as recited in claim 10 wherein said patch is elongate.

14. An infrared radiation detector as recited in claim 10 wherein said first electrically conductive layer and said multiple quantum well structure are patterned wherein at least a portion thereof has a shape substantially corresponding to said planar patch.

15. An infrared radiation detector as recited in claim 10 wherein said multiple quantum well structure is tuned for a maximum photoconductive response for infrared radiation having a wavelength in said multiple quantum well structure which is approximately eight times that of the thickness of said multiple quantum well structure.

16. An infrared detector pixel element, comprising:

a planar multiple quantum well structure for producing carriers in response to infrared radiation, said quantum well structure having first and second surfaces,

a first electrically conductive layer located on said quantum well structure first surface, said first electrically conductive layer transparent to said infrared radiation,

a second electrically conductive layer located on said quantum well structure second surface, said second electrically conductive layer transparent to said infrared radiation,

an array of planar patches conductive for said infrared radiation positioned on the surface of said first conductive layer opposite said multiple quantum well structure, each said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said quantum well structure,

an electrically conductive, planar infrared radiation reflective layer positioned on the surface of said second conductive layer opposite said multiple quantum well structure, and

wherein a resonant cavity is formed between each of said conductive patches and said reflective layer, each said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said quantum well structure.

17. An infrared detector pixel element as recited in claim 16 wherein said planar multiple quantum well structure and said first electrically conductive layer are patterned to have regions thereof between said planar patches and said second conductive layer.

18. An infrared detector pixel element as recited in claim 16 wherein each of said patches is round.

19. An infrared detector pixel element as recited in claim 16 wherein each of said patches is square.

20. An infrared detector pixel element as recited in claim 16 wherein each of said patches is elongate.

21. An infrared detector pixel element as recited in claim 16 wherein said multiple quantum well structure is tuned for a maximum photoconductive response for infrared radiation having a wavelength in said muliple quantum well structure which is approximately eight times that of the thickness of said multiple quantum well structure.

22. An infrared radiation detection imager comprising:

a planar array of pixel elements each comprising;

a planar infrared radiation sensitive structure for producing carriers in response to infrared radiation, said infrared sensitive structure having first and second surfaces,

a first electrically conductive layer proximate said infrared sensitive structure first surface and electrically connected thereto, said first electrically conductive layer transparent to said infrared radiation,

an array of planar patches conductive for said infrared radiation positioned on the surface of said first conductive layer opposite said infrared sensitive structure, each said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said infrared sensitive structure,

an electrically conductive, planar infrared radiation reflective layer positioned proximate said second surface of said infrared sensitive structure and electrically connected thereto,

wherein a resonant cavity is formed between each of said conductive patches and said reflective layer, each said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said infrared sensitive structure, and

a respective electrical conductor connected to each of said planar infrared radiation reflective layers for conveying a pixel element signal from the corresponding pixel element, wherein said pixel element signals comprise an image of said infrared radiation which is received by said imager.

23. An infrared radiation detection imager as recited in claim 22 wherein said planar, infrared radiation sensitive structure is a multiple quantum well structure.

24. An infrared radiation detection imager as recited in claim 22 wherein said planar, infrared radiation sensitive structure comprises mercury cadmium telluride.

25. An infrared radiation detection imager as recited in claim 22 including a second electrically conductive layer positioned between and electrically connected with said infrared radiation sensitive structure and said reflective layer, said second electrically conductive layer transparent to said infrared radiation.

26. An infrared radiation detection imager as recited in claim 22 wherein each of said patches is round.

27. An infrared radiation detection imager as recited in claim 22 wherein each of said patches is square.

28. An infrared radiation detection imager as recited in claim 22 wherein each of said patches is elongate.

29. An infrared radiation detection imager as recited in claim 22 wherein said first electrically conductive layer and said infrared radiation sensitive structure are patterned to have a least a portion thereof shaped to have a similar configuration to the corresponding one of said patches.

30. An infrared radiation detection imager as recited in claim 22 wherein said infrared sensitive structure is tuned for a maximum photoconductive response for infrared radiation having a wavelength in said infrared sensitive structure which is approximate eight time that of the thickness of said infrared sensitive structure.

31. A dual band infrared radiation detector pixel element, comprising:

a first set of spaced apart multiple quantum well structures for producing carriers in response to infrared radiation, each said quantum well structure having a first and a second surface,

a first patterned electrically conductive layer positioned on said first surfaces of said quantum well structures, said first electrically conductive layer transparent to said infrared radiation,

a first array of planar patches conductive for said infrared radiation and positioned respectively on the surface of said first electrically conductive layer opposite and above each of said multiple quantum well structures, each said patch in said first array having a width equal to approximately one half of a wavelength for a first band of said infrared radiation in said first set of quantum well structures,

a second electrically conductive layer in electrical contact with said second surfaces of said multiple quantum well structures in said first set, said second electrically conductive layer transparent to said infrared radiation,

a planar multiple quantum well structure, for producing carriers in response to said infrared radiation, positioned on the opposite side of said second electrically conductive layer from said first set of multiple quantum well structures,

a second array of planar patches conductive for said infrared radiation and positioned on the side of said second electrically conductive layer opposite said planar multiple quantum well structure, each said patch in said second array having a width equal to approximately one half of a wavelength for a second band of said infrared radiation in said planar multiple quantum well structure,

a third electrically conductive layer positioned on the opposite surface of said planar multiple quantum well structure from said second electrically conductive layer and in electrical contact with said planar multiple quantum well structure,

an infrared radiation reflective layer positioned on the side of said third electrically conductive layer opposite said planar multiple quantum well structure,

an infrared radiation reflective layer positioned on the side of said third electrically conductive layer opposite said plunar multiple quantum well structure, and

wherein a first set of resonant cavities are formed between each of said patches in said first array and said reflective layer, each said resonant cavity in said first set having a thickness not greater than approximately one eighth of the wavelength of said first band of said infrared radiation in said first quantum well structures, and wherein a second set of resonant cavities are formed between each of said patches in said second array and said reflective layer, each said resonant cavity in said second set having a thickness not greater than approximately one eighth of the wavelength of said second band of said infrared radiation in said planar multiple quantum well structure.

32. An infrared radiation detector pixel element as recited in claim 31 wherein said patches in the first and second arrays are round.

33. An infrared radiation detector pixel element as recited in claim 31 wherein said patches in the first and second arrays are square.

34. An infrared radiation detector pixel element as recited in claim 31 wherein said patches in the first and second arrays are elongate.

35. An infrared radiation detector pixel element as recited in claim 31 wherein said first electrically conductive layer and each of said multiple quantum well structures are patterned such that at least a portion thereof has a shape substantially corresponding to the respectively positioned first array of planar patches.

36. An infrared radiation detector as recited in claim 31 wherein each of said first multiple quantum well structures is tuned for a maximum photoconductive response for infrared radiation having a wavelength in said first multiple quantum well structure which is approximately eight times that of the thickness of said first multiple quantum well structure.

37. An infrared radiation detector comprising:

a planar, infrared radiation sensitive structure for producing carriers in response to infrared radiation, said infrared radiation sensitive structure having first and second surfaces,

a first electrically nonconductive layer proximate said infrared sensitive structure first surface, said first electrically nonconductive layer transparent to said infrared radiation,

a planar patch positioned on the surface of said first nonconductive layer opposite said infrared sensitive structure, said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said infrared sensitive structure,

a second electrically nonconductive layer proximate said second surface of said infrared sensitive structure,

a planar infrared radiation reflective layer positioned proximate said second electrically nonconductive layer opposite said infrared sensitive structure,

a first conductor in electrical contact with said infrared radiation sensitive structure at said first surface at a position offset from said planar patch,

a second conductor in electrical contact with said infrared radiation sensitive structure at said second surface at a position on said second surface offset from the corresponding location of said first conductor at said first surface, wherein current flow in said infrared radiation sensitive structure is between said first and second conductors and is substantially parallel to the plane of said infrared radiation sensitive structure, and

wherein a resonant cavity is formed between said conductive patch and said reflective layer, said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said infrared sensitive structure.

38. An infrared radiation detector as recited in claim 37 wherein said planar, infrared radiation sensitive structure comprises mercury cadmium telluride.

39. An infrared radiation detector structure comprising:

a planar, infrared radiation sensitive structure for producing carriers in response to infrared radiation, said infrared radiation sensitive structure having first and second surfaces,

a first electrically nonconductive layer proximate said infrared sensitive structure first surface, said first electrically nonconductive layer transparent to said infrared radiation,

an array of planar patches positioned on the surface of said first nonconductive layer opposite said infrared sensitive structure, each said patch having a width equal to approximately one half of a wavelength of said infrared radiation in said infrared sensitive structure,

a second electrically nonconductive layer proximate said second surface of said infrared sensitive structure,

a planar infrared radiation reflective layer positioned proximate said second electrically nonconductive layer opposite said infrared sensitive structure,

a first conductor in electrical contact with said infrared radiation sensitive structure at said first surface at a position offset from said array of planar patches,

a second conductor in electrical contact with said infrared radiation sensitive structure at said second surface at a position on said second surface offset from the corresponding location of said first conductor at said first surface, wherein current flow in said infrared radiation sensitive structure is between said first and second conductors and is substantially parallel to the plane of said infrared radiation sensitive structure, and

wherein a resonant cavity is formed between each of said conductive patches and said reflective layer, each said resonant cavity having a thickness not greater than approximately one eighth of the wavelength of said infrared radiation in said infrared sensitive structure.

40. An infrared radiation detector as recited in claim 39 wherein said planar, infrared radiation sensitive structure comprises mercury cadmium telluride.