OPTOELECTRONIC DEVICE WITH UPCONVERTING LUMINOPHORIC MEDIUM

• US 20090034201A1
• Filed: 08/02/2007
• Published: 02/05/2009
• Est. Priority Date: 08/02/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Brandes, George R.
• Granted Patent: US 8,297,061 B2
• Time in Patent Office: Days
• US Class Current: 361/704
• CPC Class Codes: C09K 11/7771 Oxysulfides
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/644 in intimate contact or integrated with parts of the device other than the semiconductor body
• CPC Class Codes: Y10T 29/4935 Heat exchanger or boiler making

Abstract

A microelectronic device that in operation generates or includes component(s) that generate heat, in which the device comprises a heat conversion medium that converts such heat into a light emission having a shorter wavelength than such heat, to thereby cool the device and dissipate the unwanted heat by such light output. The heat conversion medium can include an upconverting luminophoric material, e.g., an anti-Stokes phosphor or phosphor composition. The provision of such heat conversion medium enables thermal management of microelectronic devices, e.g., optoelectronic devices, to be achieved in an efficient manner, to prolong the operational service life of devices such as LEDs, laser diodes, etc. that are degraded in performance by excessive heat generation in their operation.

Claims

1. A microelectronic device comprising a heat-generating structure producing heat in operation of the device, and an upconverting luminophoric material that in exposure to such heat responsively converts the heat to light, to thereby cool the device and dissipate the heat by such light.

2. The microelectronic device of claim 1, wherein the upconverting luminophoric material comprises an anti-Stokes phosphor.

3. The microelectronic device of claim 2, wherein the upconverting luminophoric material comprises a material of the formula L:

M, wherein L is yttrium oxide, yttrium fluoride, yttrium oxyfluoride, yttrium oxychloride, yttrium oxysulfide, or ytterbium oxychloride, and M is one or more of ytterbium, erbium, and thulium.

4. The microelectronic device of claim 2, wherein the upconverting luminophoric material comprises a material selected from the group consisting of Y₂O₂S:

Yb,Tm;

La₂O₂S;

Er,Yb;

Y₂O₂S;

Er,Yb;

YF₃;

Er,Yb;

Y₂O₃—

YOF;

Er,Yb;

YOCl;

Er,Yb; and

YbOCl;

Er.

5. The microelectronic device of claim 1, wherein the upconverting luminophoric material is arranged to receive heat input from the heat-generating structure by conductive heat transfer.

6. The microelectronic device of claim 1, wherein the upconverting luminophoric material is arranged to receive heat input from the heat-generating structure by radiative heat transfer.

7. The microelectronic device of claim 1, wherein the heat-generating structure comprises a light emitting diode.

8. The microelectronic device of claim 7, wherein the light emitting diode is formed of a III-V nitride material.

9. The microelectronic device of claim 8, further comprising a down-converting luminophoric material arranged to receive primary radiation from the light emitting diode and to responsively emit a light output.

10. The microelectronic device of claim 9, wherein the heat-generating structure comprises the down-converting luminophoric material.

11. The microelectronic device of claim 1, comprising an optoelectronic device.

12. The microelectronic device of claim 1, wherein the heat-generating structure comprises an LED die and a down-converting luminophoric material.

13. The microelectronic device of claim 1, wherein the upconverting luminophoric material is present in a layer containing same that is coated on at least a portion of said device.

14. The microelectronic device of claim 1, wherein the upconverting luminophoric material is present in a layer containing same that is coated on at least a portion of said heat generating structure.

15. A microelectronic device generating heat in operation of the device, and an upconverting material arranged to reduce the thermal energy of the device and/or to produce light in the visible spectrum, in exposure of the upconverting material to such heat.

16. The microelectronic device of claim 15, comprising a light emitting diode or a laser diode.

17. A microelectronic device according to claim 15, including multiple upconverting materials, including a first upconverting material that is responsive to thermal energy to produce upconverted light, and a second upconverting material produces upconverting light in response to thermal energy, the upconverted light and/or energy from an active region of the microelectronic device.

25. A microelectronic device according to claim 15, including multiple upconverting and/or down-converting elements that are responsive to energy emitted by any of light emitting regions of the microelectronic device to produce a predetermined light output spectrum for the microelectronic device.

18. The microelectronic device of claim 18, further comprising a down-converting material, wherein the second upconverting material is responsive to energy produced by the down-converting material.

19. A microelectronic device including an upconverting material and a down-converting material, each arranged for energetic interaction with or within the device.

20. The microelectronic device of claim 19, wherein the upconverting material produces upconverted light in response to energy produced by the down-converting material.

21. The microelectronic device of claim 19, wherein the upconverting material comprises an anti-Stokes phosphor, and the down-converting material comprises a Stokes phosphor.

22. The microelectronic device of claim 19, wherein down-converting energy generated in operation of the device upconverts thermal energy to light energy.

23. The microelectronic device of claim 19, wherein the down-converting material is responsive to energy emitted from an active region of the microelectronic device, to produce downconverted light.

24. The microelectronic device of claim 20, wherein upconverted and downconverted light in the visible spectrum are generated in the operation of the microelectronic device.

26. A composite material comprising anti-Stokes phosphor and Stokes phosphor.

27. The composite material of claim 26, wherein each of the anti-Stokes phosphor and Stokes phosphor is in a particulate form.

28. The composite material of claim 27, wherein the particulate form anti-Stokes phosphor and Stokes phosphor are dispersed in a film-forming carrier, as a coating composition.

29. A method of thermally managing a microelectronic device generating heat in operation, comprising absorbing the heat with an upconverting luminophoric material that in exposure to such heat responsively converts the heat to a light output, to thereby cool the device and dissipate the heat by such light output.

30. The method of claim 29, wherein the upconverting luminophoric material comprises an anti-Stokes phosphor.

31. The method of claim 29, wherein the upconverting luminophoric material comprises a material of the formula L:

M, wherein L is yttrium oxide, yttrium fluoride, yttrium oxyfluoride, yttrium oxychloride, yttrium oxysulfide, or ytterbium oxychloride, and M is one or more of ytterbium, erbium, and thulium.

32. The method of claim 29, wherein the upconverting luminophoric material comprises a material selected from the group consisting of Y₂O₂S:

Yb,Tm;

La₂O₂S;

Er,Yb;

Y₂O₂S;

Er,Yb;

YF₃;

Er,Yb;

Y₂O₃—

YOF;

Er,Yb;

YOCl;

Er,Yb; and

YbOCl;

Er.

33. The method of claim 29, wherein the upconverting luminophoric material is arranged to receive heat input from a heat-generating structure of the device by conductive heat transfer or by radiative heat transfer.

34. The method of claim 29, wherein the device comprises a down-converting luminophoric material arranged to receive primary radiation from the light emitting diode and to responsively emit a light output.

35. The method of claim 34, wherein the heat is generated in the down-converting luminophoric material.

36. A method of thermally managing a microelectronic device generating heat in operation of the device, comprising reducing the thermal energy of the device by interaction thereof with an upconverting material and/or producing light in the visible spectrum, in exposure of the upconverting material to heat generated by the device.

37. The method of claim 36, wherein the microelectronic device comprises a light emitting diode or a laser diode.

38. A method according to claim 36, comprising incorporating multiple upconverting materials therein, including a first upconverting material that is responsive to thermal energy to produce upconverted light, and a second upconverting material produces upconverting light in response to thermal energy, the upconverted light and/or energy from an active region of the microelectronic device.

39. The method of claim 38, further comprising incorporating a down-converting material in the microelectronic device, wherein the second upconverting material is responsive to energy produced by the down-converting material.

40. A method of thermally managing a microelectronic device, comprising incorporating an upconverting material and a down-converting material therein, each arranged for energetic interaction in the device.

41. The method of claim 40, wherein the upconverting material produces upconverted light in response to energy produced by the down-converting material.

42. The method of claim 40, wherein the upconverting material comprises an anti-Stokes phosphor and the down-converting material comprises a Stokes phosphor.

43. The method of claim 40, wherein upconverted and downconverted light in the visible spectrum are generated in the operation of the microelectronic device.

44. A method of fabricating a microelectronic device, comprising incorporating in said microelectronic device multiple upconverting and/or down-converting elements that are responsive to energy emitted by any of light emitting regions of the microelectronic device to produce a predetermined light output spectrum for the microelectronic device.

45. A microelectronic device that in operation generates or includes component(s) that generate heat, the device comprising a heat conversion medium, including an emissive conversion material, that converts said heat into a light emission having a shorter wavelength than said heat radiation.

46. The microelectronic device of claim 45, wherein said light emission is effective to cool the microelectronic device.

47. The microelectronic device of claim 45, wherein said light emission is effective to cool the microelectronic device to a greater extent, in relation to a corresponding microelectronic device lacking said heat conversion medium wherein said heat is dissipated by radiative and conductive cooling of said microelectronic device.

48. The microelectronic device of claim 45, wherein heat is transferred from said microelectronic device or component(s) thereof to said heat conversion medium by at least one of conduction and radiation.

49. The microelectronic device of claim 45, wherein said heat conversion medium comprises multiple phosphor materials including an anti-Stokes phosphor.

50. The microelectronic device of claim 45, further comprising a visible light source, wherein said emissive conversion material emits light comprised in said light emission, in response to light emitted by said visible light source.

51. The microelectronic device of claim 45, wherein said component(s) that generate heat comprise comprise at least one of a down-converting luminophoric material and a light emitting diode.

52. The microelectronic device of claim 45, wherein the heat conversion medium comprises multiple upconverting materials, including a first upconverting material that is responsive to said heat to produce upconverted light, and a second upconverting material producing upconverted light in response to said heat, said upconverted light from said first upconverting material and/or energy from an active region of the microelectronic device.

53. The microelectronic device of claim 45, including an upconverting material and a down-converting material, each arranged for energetic interaction in the device.

54. The microelectronic device of claim 45, wherein said emissive conversion material upconverts energy from a phosphor.

55. The microelectronic device of claim 45, comprising a luminophoric medium that downconverts energy from a light emitting diode or a phosphor.

56. A microelectronic device that in operation generates or includes component(s) that generate heat, the device comprising a heat conversion medium that converts said heat to a light emission that is effective to dissipate said heat.

57. A microelectronic device that in operation generates or includes component(s) that generate heat, in which the device comprises an upconverting material that produces upconverted light in response to heat, an external light source and/or energy from an active region of the microelectronic device.

58. A method of thermally managing a microelectronic device, comprising incorporating therein an upconverting material that produces upconverted light in response to heat, an external light source and/or energy from an active region of the microelectronic device.