LIGHT EMITTING DEVICE HAVING STACKED MULTIPLE LEDS

• US 20090272989A1
• Filed: 05/30/2008
• Published: 11/05/2009
• Est. Priority Date: 05/01/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Bridgelux Incorporated
• Inventors: Liu, Heng, Shum, Frank
• Granted Patent: US 7,732,803 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• 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

Abstract

A light emitting device and method of producing the same is disclosed. The light emitting device includes a heterostructure having a plurality of light emitting diodes (LEDs) stacked one on top of another.

Claims

1. A light emitting device, comprising:

a heterostructure having a plurality of light emitting diodes (LEDs) stacked one on top of another.

2. The light emitting device of claim 1, wherein each of the LEDs is configured to be independently biased.

3. The light emitting device of claim 1, wherein each of the LEDs has independently controllable light output.

4. The light emitting device of claim 1, further comprising an ohmic contact layer provided between two of the LEDs.

5. The light emitting device of claim 1, further comprising a substrate, wherein the LEDs are provided on one side of the substrate.

6. The light emitting device of claim 5, wherein the substrate is conductive and transparent.

7. The light emitting device of claim 6, wherein at least one of the LEDs is configured to be biased through the substrate.

8. The light emitting device of claim 6, further comprising a reflective surface provided on a side of the substrate that is opposite the side on which the LEDs are provided.

9. The light emitting device of claim 1, wherein each of the LEDs includes a n-type semiconductor layer and a p-type semiconductor layer.

10. The light emitting device of claim 9, wherein the light emitting device emits light when a voltage applied to the n-type semiconductor layer of at least one of the LEDs is equal to a voltage applied to the n-type semiconductor layer of at least another one of the LEDs.

11. The light emitting device of claim 10, wherein the light emitting device emits light when a voltage applied to the p-type semiconductor layer of at least one of the LEDs is equal to a voltage applied to the p-type semiconductor layer of at least another one of the LEDs.

12. The light emitting device of claim 1, wherein the light emitting device emits light when a direction of flow of an electric current across a p-n junction of at least one of the LEDs is opposite to a direction of flow of an electric current across a p-n junction of at least another one of the LEDs.

13. The light emitting device of claim 1, wherein each of the LEDs emits a light of a different wavelength.

14. A method for producing a light emitting device, comprising:

stacking a plurality of light emitting diodes (LEDs) one on top of another so as to form a layered structure.

15. The method of claim 14, further comprising configuring each of the LEDs to be independently biased.

16. The method of claim 14, further comprising configuring each of the LEDs to have independently controllable luminance.

17. The method of claim 14, further comprising providing an ohmic contact layer between two of the LEDs.

18. The method of claim 14, further comprising providing the LEDs on one side of a substrate.

19. The method of claim 18, wherein the substrate is conductive and transparent.

20. The method of claim 19, further comprising configuring at least one of the LEDs to be biased through the substrate.

21. The method of claim 19, further comprising providing a reflective surface on a side of the substrate that is opposite the side on which the LEDs are provided.

22. The method of claim 14, wherein each of the LEDs includes a n-type semiconductor layer and a p-type semiconductor layer.

23. A method for producing light from a light emitting device having a plurality of light emitting diodes (LEDs), wherein the plurality of LEDs are stacked one on top of another so as to form a layered structure, and wherein each of the LEDs includes a n-type semiconductor layer and a p-type semiconductor layer, the method comprising:

applying a first voltage to the n-type semiconductor layer of at least one of the LEDs; and

applying the first voltage to the n-type semiconductor layer of at least another one of the LEDs.

24. The method of claim 23, further comprising:

applying a second voltage to the p-type semiconductor layer of at least one of the LEDs; and

applying the second voltage to the p-type semiconductor layer of at least another one of the LEDs.

25. The method of claim 23, further comprising:

inducing a first electric current across a p-n junction of at least one of the LEDs; and

inducing a second electric current across a p-n junction of at least another one of the LEDs,

wherein a direction of flow of the first electric current is opposite to a direction of flow of the second electric current.

26. The method of claim 23, further comprising causing each of the LEDs to emit a light of a different wavelength.