Spatial localization of light-generating portions in LEDs

• US 20080135861A1
• Filed: 12/08/2006
• Published: 06/12/2008
• Est. Priority Date: 12/08/2006
• Status: Active Grant

• Current Assignee: Luminus Devices Incorporated (Sanan Optoelectronics Company Limited)
• Original Assignee: Luminus Devices Incorporated (Sanan Optoelectronics Company Limited)
• Inventors: Nemchuk, Nikolay I., Lim, Michael, Pokrovskiy, Alexander L., Erchak, Alexei A., Minsky, Milan Singh
• Granted Patent: US 8,110,838 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

Light-emitting devices (e.g., LEDs) and methods associated with such devices are provided. In some embodiments, the device includes a distribution of light-generating portions (including active regions) that are spatially localized and separated (e.g., horizontally or vertically) from one or more patterned light extraction portions. This arrangement can allow light generated by the device to propagate and pass through regions of low absorption (e.g., light-extraction portions) rather than in regions of high absorption (e.g., light-generating portions), which can enhance light emission. In some instances, the devices include one or more series of light extraction portions with features arranged in a first and/or second pattern, which may be formed on one or more interfaces of the device (e.g., an emission surface). Patterns can be defined by a series of features (e.g., holes) having certain characteristics (e.g., feature size, depth, nearest neighbor distances) which may be controlled to influence properties of the light emitted from the device, including improving extraction and/or collimation of the emitted light.

Claims

1. A light-emitting device comprising:

a distribution of light-generating portions configured to generate light; and

at least one light extraction portion that allows generated light to pass therethrough, wherein the light extraction portion is devoid of a light-generating portion.

2. A light-emitting device of claim 1, wherein the light-extraction portion comprises a dielectric function that varies spatially according to a first pattern.

3. A light-emitting device of claim 1, wherein a layer positioned above an active region of the light-generating portion comprises a dielectric function that varies spatially according to a second pattern.

4. A light-emitting device of claim 2, wherein the first pattern is a photonic lattice.

5. A light-emitting device of claim 3, wherein the second pattern is a photonic lattice.

6. A light-emitting device of claim 3, wherein the first pattern is different from the second pattern.

7. A light-emitting device of claim 1, further comprising a plurality of light extraction portions.

8. A light-emitting device of claim 1, wherein at least a part of a light-generating portion is not positioned above or below the light extraction portion.

9. A light-emitting device of claim 1, wherein at least one light-generating portion is not positioned above or below the light extraction portion.

10. A light-emitting device of claim 7, wherein the light-generating portions are laterally separated from the light extraction portions.

11. A light-emitting device of claim 1, wherein at least one light-generating portion has a cross-sectional dimension equal to or less than a cross-sectional dimension of at least one light extraction portion.

12. A light-emitting device of claim 7, wherein the light extraction portions have a plurality of features that vary spatially according to a pattern.

13. A light-emitting device of claim 12, wherein the features are holes in a surface of the light extraction portions.

14. A light-emitting device of claim 1, wherein the light extraction portion comprises an optically reflective region.

15. A light-emitting device of claim 14, wherein the optically reflective region comprises a focusing element.

16. A light-emitting device of claim 14, wherein the optically reflective region comprises an optically reflective layer.

17. A light-emitting device comprising:

a distribution of light-generating portions configured to generate light; and

at least one light extraction portion that allows generated light to pass therethrough, wherein at least a part of the light extraction portion comprises a dielectric function that varies spatially according to a pattern.

18. A light-emitting device of claim 17, wherein at least one light-generating portion comprises a dielectric function that varies spatially according to a second pattern.

19. A light-emitting device of claim 17, wherein a light extraction portion is positioned above the light-generating portion.

20. A light-emitting device of claim 17, wherein the pattern is a photonic lattice.

21. A light-emitting device of claim 17, wherein at least a part of one light-generating portion is not positioned above or below the light extraction portion.

22. A light-emitting device of claim 17, further comprising a plurality of light extraction portions.

23. A light-emitting device of claim 17, wherein at least one light-generating portion has a cross-sectional dimension equal to or than a cross-sectional dimension of the light extraction portion.

24. A light-emitting device comprising:

a distribution of light-generating portions configured to generate light, wherein a surface of at least one of the light-generating portions has a dielectric function that varies spatially according to a first pattern; and

at least one light extraction portion that allows generated light to pass therethrough, wherein a surface of the light extraction portion has a dielectric function that varies spatially according to a second pattern.

25. A light-emitting device comprising:

a first light-generating portion configured to generate light of one wavelength; and

a second light-generating portion configured to generate light of a different wavelength than the first light-generating portion, wherein the second light-generating portion does not substantially absorb light emitted by the first light-generating region, and wherein a surface of the second light-generating portion has a dielectric function that varies spatially according to a pattern.

26. A light-emitting device comprising:

an active region configured to generate light;

a light extraction region that allows generated light to pass therethrough, the light extraction region comprising a layer including a dielectric function that varies spatially according to a pattern; and

a low refractive index layer supported by the active region and supporting the layer including the dielectric function, the low refractive index layer having a lower refractive index than that of the active region.

27. A light-emitting device of claim 26, wherein the low refractive index layer is directly supported by the active region.

28. A light-emitting device of claim 26, wherein the low refractive index layer directly supports the layer including the dielectric function.

29. A light-emitting device of claim 26, wherein the low refractive index layer has an index of refraction of less than 2.5.

30. A light-emitting device of claim 26, wherein the pattern is a photonic lattice.

31. A light-emitting device comprising:

a distribution of light-generating portions configured to generate light, each light-generating portion including an active region; and

at least one emission surface that allows generated light to pass therethrough, wherein at least a part of an active region is not positioned above or below the emission surface.