Single or multi-color high efficiency light emitting diode (LED) by growth over a patterned substrate

• US 7,291,864 B2
• Filed: 02/28/2005
• Issued: 11/06/2007
• Est. Priority Date: 02/28/2005
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Speck, James S., DenBaars, Steven P., David, Aurelien J. F., Weisbuch, Claude C. A.
• Primary Examiner(s): Huynh; Andy
• Application Number:
  US11/067,910
• Publication Number:
  US 20060202226A1
• Time in Patent Office: 981 Days
• Field of Search: 257/98, 257/79, 257/435, 257/436, 257/E33.067, 257/E51.021
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction

Abstract

A single or multi-color light emitting diode (LED) with high extraction efficiency is comprised of a substrate, a buffer layer formed on the substrate, one or more patterned layers deposited on top of the buffer layer, and one or more active layers formed on or between the patterned layers, for example by Lateral Epitaxial Overgrowth (LEO), and including one or more light emitting species, such as quantum wells. The patterned layers include a patterned, perforated or pierced mask made of insulating, semiconducting or metallic material, and materials filling holes in the mask. The patterned layer acts as an optical confining layer due to a contrast of a refractive index with the active layer and/or as a buried diffraction grating due to variation of a refractive index between the mask and the material filling the holes in the mask.

Claims

1. A light emitting diode (LED), comprising:

(a) one or more patterned layers, wherein each patterned layer comprises a mask and materials filling holes in the mask; and

(b) one or more active layers formed on or between the patterned layers, wherein the active layers include one or more light emitting species;

(c) wherein each patterned layer acts as an optical confining layer or a buried diffraction grating for the light emitting species of the active layer.

2. The LED of claim 1, further comprising a substrate and a buffer layer grown on the substrate, wherein the patterned layer is deposited on top of the buffer layer.

3. The LED of claim 2, wherein the buffer layer is a gallium nitride (GaN)-based material.

4. The LED of claim 1, wherein the patterned layer acts as an optical confining layer due to a contrast of a refractive index with the active layer.

5. The LED of claim 1, wherein the patterned layer acts as a buried diffraction grating due to variations of a refractive index between the mask and the materials filling holes in the mask.

6. The LED of claim 1, wherein the active layer is a gallium nitride (GaN)-based material.

7. The LED of claim 1, wherein the active layer is grown by Lateral Epitaxial Overgrowth (LEO).

8. The LED of claim 1, wherein the mask is comprised of an insulating, semiconducting or metallic material.

9. The LED of claim 1, where the materials filling the holes in the mask comprise gallium nitride (GaN)-based materials.

10. The LED of claim 1, wherein the materials filling hales in the mask are grown by Lateral Epitaxial Overgrowth (LEO).

11. The LED of claim 1, further comprising mirrors placed above or below the patterned layer, to enhance or decrease emissions in a desired direction.

12. The LED of claim 1, wherein different patterns in the patterned layer are used to extract different wavelengths by diffraction or to vary a direction of the diffraction.

13. The LED of claim 1, wherein additional active optically-pumped regions are used to recycle the guided modes, thus re-emitting a portion of guided modes at another frequency.

14. The LED of claim 1, wherein the LED has separate emission and extraction zones.

15. The LED of claim 1, wherein the LED has separate emission and diffraction regions.

16. The LED of claim 1, where emission from the active layers occurs mainly in certain directions by suitable tailoring of the LED'"'"'s guided modes structure, in order to produce a directional LED.

17. A method of fabricating a light emitting diode (LED), comprising:

(a) depositing one or more patterned layers, wherein each patterned layer comprises a mask and materials filling holes in the mask; and

(b) forming one or more active layers on or between the patterned layers, wherein the active layers include one or more light emitting species;

(c) wherein the patterned layer acts as an optical confining layer or a buried diffraction grating for the light emitting species of the active layer.

18. The method of claim 17, further comprising a substrate and a buffer layer grown on the substrate, wherein the patterned layer is deposited on top of the buffer layer.

19. The method of claim 18, wherein the buffer layer is a gallium nitride (GaN)-based material.

20. The method of claim 17, wherein the patterned layer acts as an optical confining layer due to a contrast of a refractive index with the active layer.

21. The method of claim 17, wherein the patterned layer acts as a buried diffraction grating due to variations of a refractive index between the mask and the materials filling holes in the mask.

22. The method of claim 17, wherein the active layer is a gallium nitride (GaN)-based material.

23. The method of claim 17, wherein the active layer is grown by Lateral Epitaxial Overgrowth (LEO).

24. The method of claim 17, wherein the mask is comprised of an insulating, semiconducting or metallic material.

25. The method of claim 17, where the materials filling the holes in the mask comprise gallium nitride (GaN)-based materials.

26. The method of claim 17, wherein the materials filling holes in the mask are grown by Lateral Epitaxial Overgrowth (LEO).

27. The method of claim 17, further comprising placing mirrors above or below the patterned layer, to enhance or decrease emissions in a desired direction.

28. The method of claim 17, wherein different patterns in the patterned layer are used to extract different wavelengths by diffraction or to vary a direction of the diffraction.

29. The method of claim 17, wherein additional active optically-pumped regions are used to recycle the guided modes, thus re-emitting a portion of guided modes at another frequency.

30. The method of claim 17, wherein the LED has separate emission and extraction zones.

31. The method of claim 17, wherein the LED has separate emission and diffraction regions.

32. The method of claim 17, wherein emission from the active layers occurs mainly in certain directions by suitable tailoring of the LED'"'"'s guided modes structure, in order to produce a directional LED.

33. A device fabricated using the method of claim 17.