SINGLE OR MULTI-COLOR HIGH EFFICIENCY LIGHT EMITTING DIODE (LED) BY GROWTH OVER A PATTERNED SUBSTRATE

• US 20100295081A1
• Filed: 06/04/2010
• Published: 11/25/2010
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• 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.
• Granted Patent: US 8,390,011 B2
• Time in Patent Office: Days
• 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. An opto-electronic device, comprising:

(a) an active layer formed over a patterned layer that includes a patterned, pierced or perforated mask;

(b) wherein the patterned layer uses the mask to control light emissions of the active layer into radiative and guided modes.

2. The device of claim 1, wherein the active layer formed over the patterned layer is a Lateral Epitaxial Overgrowth (LEO) layer.

3. The device of claim 1, wherein the patterned layer acts both as an optical confinement layer and as a buried diffraction grating, thus controlling the light emissions of the active layer into the radiative and guided modes.

4. The device of claim 1, wherein, due to an index difference between the active layer and the patterned layer, the light emissions'"'"' pattern of the active layer is modified to increase or decrease a relative amount of light emitted in the radiative and guided modes.

5. The device of claim 1, wherein the mask is made of an insulating, semiconducting or metallic material.

6. The device of claim 1, wherein the patterned layer further comprises materials filling holes in the mask.

7. The device of claim 6, wherein, due to variations of a refractive index between the mask and the materials filling the holes in the mask, the patterned layer acts as a diffraction grating, thus enabling the guided modes to be emitted outside of the device.

8. The device of claim 1, wherein geometries for patterns, perforations or piercings in the mask comprise square arrays, rectangular arrays, Archimedean tilings, or random patterns.

9. The device of claim 1, wherein different patterns in the mask have different periods to extract different wavelengths of the light emissions by diffraction.

10. The device of claim 1, wherein parameters of the mask or patterned layer, such as holes shape, size or depth and thickness of the mask or the patterned layer, are varied spatially in order to have different properties of the mask or the patterned layer, in different regions of the device.

11. The device of claim 1, wherein the active layer includes at least two light-emitting species emitting at different wavelengths and the patterned layer includes at least two patterns.

12. The device of claim 1, wherein one or more mirrors are placed above or below the patterned layer to enhance or decrease the light emissions in a desired direction.

13. The device of claim 1, further comprising additional active optically-pumped regions that are used to recycle the guided modes, thus re-emitting a portion of the light emissions at another frequency.

14. The device of claim 1, wherein the active layer and the patterned layer comprise a directional light source, such that the light emissions occur mainly in certain directions by suitable tailoring of the patterned layer.

15. A method of fabricating an opto-electronic device, comprising:

(a) forming an active layer over a patterned layer that includes a patterned, pierced or perforated mask;

(b) wherein the patterned layer uses the mask to control light emissions of the active layer into radiative and guided modes.

16. The method of claim 15, wherein the active layer formed over the patterned layer is a Lateral Epitaxial Overgrowth (LEO) layer.

17. The method of claim 15, wherein the patterned layer acts both as an optical confinement layer and as a buried diffraction grating, thus controlling the light emissions of the active layer into the radiative and guided modes.

18. The method of claim 15, wherein, due to an index difference between the active layer and the patterned layer, the light emissions'"'"' pattern of the active layer is modified to increase or decrease a relative amount of light emitted in the radiative and guided modes.

19. The method of claim 15, wherein the mask is made of an insulating, semiconducting or metallic material.

20. The method of claim 15, wherein the patterned layer further comprises materials filling holes in the mask.

21. The method of claim 20, wherein, due to variations of a refractive index between the mask and the materials filling the holes in the mask, the patterned layer acts as a diffraction grating, thus enabling the guided modes to be emitted outside of the device.

22. The method of claim 15, wherein geometries for patterns, perforations or piercings in the mask comprise square arrays, rectangular arrays, Archimedean tilings, or random patterns.

23. The method of claim 15, wherein different patterns in the mask have different periods to extract different wavelengths of the light emissions by diffraction.

24. The method of claim 15, wherein parameters of the mask or patterned layer, such as holes shape, size or depth and thickness of the mask or the patterned layer, are varied spatially in order to have different properties of the mask or the patterned layer, in different regions of the device.

25. The method of claim 15, wherein the active layer includes at least two light-emitting species emitting at different wavelengths and the patterned layer includes at least two patterns.

26. The method of claim 15, wherein one or more mirrors are placed above or below the patterned layer to enhance or decrease the light emissions in a desired direction.

27. The method of claim 15, further comprising fabricating additional active optically-pumped regions that are used to recycle the guided modes, thus re-emitting a portion of the light emissions at another frequency.

28. The method of claim 15, wherein the active layer and the patterned layer comprise a directional light source, such that the light emissions occur mainly in certain directions by suitable tailoring of the patterned layer.

29. A device fabricated using the method of claim 15.