Radiation source

• US 6,876,006 B1
• Filed: 04/21/2000
• Issued: 04/05/2005
• Est. Priority Date: 04/27/1999
• Status: Expired due to Term

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Talalakin, Georgii, Karandashov, Sergey, Remennyi, Maxim, Stus', Nikolai, Zotova, Nonna, Il'Inskaya, Natalia, Matveev, Boris
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US10/031,251
• Time in Patent Office: 1,810 Days
• Field of Search: 257/85, 257/80, 257/89, 257/90, 257/98, 257/81, 257/83
• US Class Current: 257/85
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 25/0756 Stacked arrangements of devices
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/0008 having p-n or hi-lo junctions
• CPC Class Codes: H01L 33/0025 comprising only AIIIBV compounds
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

A radiation source (30) is provided comprising a first active layer (42) coupled to a second active layer (62), wherein the first active layer (42) produces primary radiation of frequency v₁ by appropriate stimulation, and the primary radiation is converted by the second active layer (62) to secondary radiation of frequency v₂ for subsequent output. The coupling between the first and second active layers is achieved by an intermediary layer (58) disposed between the first active layer (42) and the second active layer (62). The radiation source (30) further comprises a p-n junction (48) incorporated in the first active layer (42), where injection of electrical carriers into the first active layer (42) from the p-n junction stimulates the first active layer (42) to emit the primary radiation.

Claims

1. A radiation source comprising a first active layer coupled to a second active layer, wherein the first and second active layers are separate, the first active layer produces primary radiation of frequency v_i by appropriate stimulation, and the primary radiation is converted by the second active layer to secondary radiation of frequency v₂ for subsequent output and wherein coupling occurs by an intermediary layer disposed between the first active layer and the second active layer, the intermediary layer comprising a noncrystalline material.

2. A radiation source according to claim 1, wherein additional active layers are provided, such that each active layer is coupled to a previous active layer, and each active layer subsequent to the first active layer modifies the radiation produced by the previous active layer.

3. A radiation source according to claim 1, wherein the intermediary layer is substantially optically transparent to the primary radiation, so providing optical coupling between the first active layer and the second active layer.

4. A radiation source according to claim 1, wherein the intermediary layer has a refractive index n which is less than 1, and less than or equal to the refractive index of the active layers positioned either side of the intermediary layer.

5. A radiation source according to claim 1, wherein the first active layer comprises a semiconductor junction.

6. A radiation source according to claim 1, wherein the radiation source further comprises an injection region incorporated in the first active layer, where injection of electrical carriers into the first active layer from the injection region stimulates the first active layer to emit the primary radiation.

7. A radiation source according to claim 6, wherein the injection region is a p-n junction.

8. A radiation source according to claim 1, wherein a first band gap energy is associated with the first active layer, and a second band gap energy is associated with the second active layer, the first band gap energy being much greater than the second band gap energy.

9. A radiation source according to claim 1, wherein the active layers satisfy the following conditions:

hv_max≦

E_subsequent+E_f*k<

E_previous

1/α

_entry≦

d≦

1/α

_exit

where hv_max is the maximum energy for the radiation produced in a subsequent active layer optically connected with a previous active layer;

E_previous is the band gap energy of the previous active layer;

E_subsequent, E_f are the band gap energy and the Fermi energy level of the active layer, respectively;

d is the thickness of the subsequent active layer;

α

_entry and α

_exit are the effective absorption coefficients for the radiation entering and exiting the subsequent active layer, respectively.

10. A radiation source according to claim 1, wherein the active layers are made of A³B⁵ material and/or its solid solutions.

11. A radiation source according to claim 10, wherein at least one active layer comprises InAs_1-x-ySb_lP_y, where x+y<

1.

12. A radiation source according to claim 10, wherein at least one active layer comprises In_1-vGa_vAs_1-wSb_w, where x+y<

1, w<

1 and v<

1.

13. A radiation source according to claim 1, wherein the first active layer and the second active layer are made from a material with a graded variation in band gap energy.

14. A radiation source according to claim 2, wherein the additional active layers are made from a material with a graded variation in the band gap energy.

15. A radiation source according to claim 14, wherein the material with a graded variation possesses the radial symmetry of a unit cell.

16. A radiation source according to claim 14, wherein the material with a graded variation adjoins the injection region along one edge where the material has a narrow band gap energy.

17. A radiation source according to claim 1, wherein the radiation source is a light emitting diode.

18. A radiation source according to claim 1, in which the intermediary layer comprises two bonding layers each attached to a respective active layer, and a heat sink layer interposed between the two bonding layers, the heat sink layer being operable to conduct heat away from the active layers.

19. A radiation source according to claim 18, in which the heat sink layer is composed of sapphire.

20. A radiation source according to claim 19, in which each bonding layer is composed of chalcogenic glass and the sapphire layer is sandwiched between the glass layers.

21. A radiation source according to claim 1, wherein the output of the radiation source is in the IR frequency range.

22. A radiation source according to claim 1, in which an optical fibre is attached to the second active layer.

23. A radiation source according to claim 1, wherein the active layers are made of a semi conductor material.

24. A radiation source according to claim 1, in which the intermediary layer is made of polymer compounds and parafins or liquids.

25. A radiation source according to claim 1, in which the intermediary layer is made of chalcogenic glass.

26. A radiation source according to claim 1, in which the source has a coating in contact with an active layer or active layer cap, said coating reducing internal reflection losses.

27. A radiation source according to claim 26 in which the coating is of chalcogenic glass.

28. A radiation source according to claim 26, in which the coating forms a Weierstrass sphere for forming a narrow far field pattern.

29. An infrared radiation source comprising a first active semiconductor layer coupled to a second active semiconductor layer, wherein the first active layer produces primary radiation of frequency v_i by appropriate stimultaion, and the primary radiation is converted by the second active layer to secondary radiation of frequency v₂ for subsequent output, and an intermediary layer disposed between the first semiconductor layer and the second semiconductor layer.

30. A radiation source according to claim 29, wherein additional active layers are provided, such that each active layer is coupled to a previous active layer, and each active layer subsequent to the first active layer modifies the radiation produced by the previous active layer.

31. A radiation source according to claim 29, wherein the intermediary layer is substantially optically transparent to the primary radiation, so providing optical coupling between the first active layer and the second active layer.

32. A radiation source according to claim 29, wherein the intermediary layer has a refractive index n which is greater than 1, and less than or equal to the refractive index of the active layers positioned either side of the intermediary layer.

33. A radiation source according to preceding claim 29, wherein the radiation source further comprises an injection region incorporated in the first active layer, where injection of electrical carriers into the first active layer from the injection region stimulates the first active layer to emit the primary radiation.

34. A radiation source according to claim 33, wherein the injection regions is a p-n junction.

35. A radiation source according to claim 29, wherein a first band gap energy is associated with the first active layer, and a second band gap energy is associated with the second active layer, the first band gap energy being much greater than the second band gap energy.

36. A radiation source according to claim 29, wherein the active layers satisfy the following conditions:

hv_max≦

E_subsequent+Ef*k<

E_previous 

 

(1)

1/α

_entry≦

d<

1/α

_exit 

 

(2)

where hv_max is the maximum energy for the radiation produced in a subsequent active layer optically connected with a previous active layer;

E_previous is the band gap energy of the previous active layer;

E_subsequents, E_f are the band gap energy and the Fermi energy level of the active layer, respectively;

d is the thickness of the subsequent active layer;

α

_entry and α

_exit are the effective absorption coefficients for the radiation entering and exiting the subsequent active layer, respectively.

37. A radiation source according to claim 29, wherein the layers are made of A3B5 material and/or its solid solutions.

38. A radiation source according to claim 29, wherein the first active layer and the second active layer are made from a material with a graded variation in band gap energy.

39. A radiation source according to claim 30, wherein the additional active layers are made from a material with a graded variation in the band gap energy.

40. A radiation source according to claim 39, wherein the material with a graded variation possesses the radial symmetry of a unit cell.

41. A radiation source according to claim 40, wherein the material with a graded variation adjoins the injection region along one edge where the material has a narrow band gap energy.

42. A radiation source according to claim 29, wherein the radiation source is a light emitting diode.

43. A radiation source according to claim 29, in which the intermediary layer comprises two bonding layers each attached to a respective active layer, and a heat sink layer interposed between the two bonding layers, the heat sink layer being operable to conduct heat away from the active layers.

44. A radiation source according to claim 43, in which the heat sink layer is composed of sapphire.

45. A radiation source according to claim 44, in which each bonding layer is composed of chalcogenic glass and the sapphire layer is sandwiched between the glass layers.

46. A radiation source according to claim 29, in which the intermediary layer is made of polymer compounds and parafins or liquids.

47. A radiation source according to claim 29, in which the intermediary layer is made of chalcogenic glass.

48. A radiation source according to claim 29, in which the source has a coating in contact with an active layer or active layer cap, said coating reducing internal reflection losses.

49. a radiation source according to claim 48 in which the coating forms a Weierstrass sphere for forming a narrow far field pattern.