Light emitting device including an electroconductive layer

• US 6,686,581 B2
• Filed: 06/26/2001
• Issued: 02/03/2004
• Est. Priority Date: 06/29/2000
• Status: Expired due to Fees

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Van Leth, Nicolaas Joseph Martin, Verhoeckx, Godefridus Johannes, Visser, Cornelis Gerardus
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US09/891,666
• Publication Number:
  US 20020014838A1
• Time in Patent Office: 952 Days
• Field of Search: 250/552, 250/553, 250/214.R, 250/462.1, 250/458.1, 250/459.1, 250/484.4, 204/485-488, 204/490
• US Class Current: 250/214.00R
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• 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

Abstract

A LED is covered with an electroconductive layer, and a luminescent layer is deposited on the electroconductive layer by electrophoresis. The conductivity of the electroconductive layer is chosen to be such that the layer can be used as one of the electrodes during the electrophoresis, while the LED is not short-circuited by the electroconductive layer during normal operation.

Claims

1. An optoelectric element, comprising:

a semiconductor light emitting device;

an electroconductive layer covering at least a portion of said light emitting device; and

a luminescent layer overlying and adjacent to said electroconductive layer, said luminescent layer for converting any electromagnetic radiation of a first wavelength range generated by said semiconductor light emitting device into a visible light of a different wavelength range;

wherein the electroconductive layer has an electrical conductivity that limits an amount of current flowing through said electroconductive layer to less than 5% of any current flowing through said light emitting device.

2. The optoelectric element of claim 1, wherein said electroconductive layer is transparent to any electromagnetic radiation generated by said light emitting device.

3. The optoelectric element of claim 1, wherein said electroconductive layer includes a transparent metal oxide.

4. The optoelectric element of claim 1, wherein said electroconductive layer includes at least one oxide chosen from an oxide group formed by indium tin oxide, antimony tin oxide, and tin oxide.

5. The optoelectric element of claim 1, wherein said light emitting device is a light emitting diode.

6. The optoelectric element of claim 1, further comprising:

a heat sink supporting said light emitting device, wherein said electroconductive layer covers each surface area of said light emitting device uncovered by said heat sink.

7. The optoelectric element of claim 6, wherein said electroconductive layer covers at least a portion of said heat sink.

8. The optoelectric element of claim 1, wherein the semiconductor light emitting device comprises:

a substrate formed from an electrically insulating material; and

a plurality of semiconductor layers provided on said substrate.

9. The optoelectric element of claim 1, further comprising electrodes formed on the light emitting device, wherein the electroconductive layer connects the electrodes.

10. The optoelectric element of claim 1, wherein the luminescent layer has a uniform thickness.

11. The optoelectric element of claim 1, wherein any current flowing through said electroconductive layer is at most 1% of any current flowing through said light emitting device.

12. The optoelectric element of claim 1, wherein an electric conductivity of the electroconductive layer is less than an electric conductivity of the light emitting device.

13. The optoelectric element of claim 1, wherein an electric conductivity of the electroconductive layer is greater than an electric conductivity of the luminescent layer.

14. The optoelectric element of claim 1, further comprising:

a submount; and

at least one solder ball connecting the light emitting device to the submount.

15. The optoelectric element of claim 14, wherein the submount comprises a Si wafer covered with a layer of aluminum.

16. A method for covering an optoelectric element with a luminescent layer, said method comprising:

providing a semiconductor light emitting device;

covering a surface of said semiconductor light emitting device with an electroconductive layer, an electric conductivity of said electroconductive layer being lower than an electric conductivity of said semiconductor light emitting device;

bringing the electronconductive layer in contact with a suspension of luminescent material; and

applying a voltage across the electroconductive layer and the suspension to deposit a layer of luminescent material on the electroconductive layer by an electrophoresis on the surface of the electroconductive layer, wherein the electric conductivity of said electronconductive layer is higher than an electric conductivity of the suspension of luminescent material.

17. The method of claim 16, further comprising:

supporting said light emitting device on a heat sink; and

covering each surface area of the light emitting device uncovered by the heat sink with the electroconductive layer.

18. The method of claim 16, wherein applying a voltage comprises maintaining a potential difference between the electroconductive layer and an electrode present in the suspension of luminescent material.

19. The method of claim 18, further comprising:

covering at least a portion of the heat sink with an electroconductive layer.

20. An optoelectric element, comprising:

a semiconductor light emitting device having a first surface, a second surface substantially parallel to said first surface, and a third surface connecting at least a portion of said first surface to a portion of said second surface;

an electroconductive layer covering at least a portion of said first and third surfaces of the light emitting device; and

a luminescent layer overlying said electroconductive layer, said luminescent layer for converting any electromagnetic radiation of a first wavelength range generated by said semiconductor body into a visible light of a different wavelength range.

21. The optoelectric element of claim 20, wherein any current flowing through said electroconductive layer is less than 5% of any current flowing through said light emitting device.

22. The optoelectric element of claim 20, wherein said electroconductive layer is transparent to any electromagnetic radiation generated by said light emitting device.

23. The optoelectric element of claim 20, wherein said electroconductive layer includes a transparent metal oxide.

24. The optoelectric element of claim 20, wherein said electroconductive layer includes at least one oxide chosen from an oxide group formed by indium tin oxide, antimony tin oxide, and tin oxide.

25. The optoelectric element of claim 20, wherein said light emitting device is a light emitting diode.

26. The optoelectric element of claim 20, wherein the semiconductor light emitting device comprises:

a substrate formed from an electrically insulating material; and

a plurality of semiconductor layers provided on said substrate.

27. The optoelectric element of claim 20, further comprising electrodes formed on the light emitting device, wherein the electroconductive layer connects the electrodes.

28. The optoelectric element of claim 20, wherein the luminescent layer has a uniform thickness.

29. The optoelectric element of claim 20, wherein any current flowing through said electroconductive layer is at most 1% of any current flowing through said light emitting device.

30. The optoelectric element of claim 20, wherein an electric conductivity of the electroconductive layer is less than an electric conductivity of the light emitting device.

31. The optoelectric element of claim 20, wherein an electric conductivity of the electroconductive layer is greater than an electric conductivity of the luminescent layer.

32. The optoelectric element of claim 20, further comprising:

a submount; and

at least one solder ball connecting the second surface of the light emitting device to the submount.

33. The optoelectric element of claim 32 wherein the submount comprises a Si wafer covered with a layer of aluminum.

34. The optoelectric element of claim 32, further comprising:

a heat sink supporting said submount, wherein said electroconductive layer covers each surface area of said submount uncovered by said heat sink.

35. The optoelectric element of claim 34, wherein said electroconductive layer covers at least a portion of said heat sink.