Light-emitting devices with high light collimation

• US 7,301,271 B2
• Filed: 02/07/2005
• Issued: 11/27/2007
• Est. Priority Date: 04/15/2003
• Status: Expired due to Term

• Current Assignee: Formosa Epitaxy Incorporated (Ennostar, Inc.)
• Original Assignee: Luminus Devices Incorporated (Sanan Optoelectronics Company Limited)
• Inventors: Erchak, Alexei A., Lidorikis, Elefterios, Luo, Chiyan
• Primary Examiner(s): WILLIAMS, JOSEPH L
• Application Number:
  US11/052,592
• Publication Number:
  US 20050151125A1
• Time in Patent Office: 1,023 Days
• Field of Search: 313498-512, 313110-116, 372 43- 49, 257/466
• US Class Current: 313/498
• 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 33/0093 Wafer bonding; Removal of the growth substrate
• 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
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

Light-emitting devices, and related components, systems and methods are disclosed. In some embodiments, the devices (e.g., light-emitting diodes) comprise a multi-layer stack of materials including a light generating region and a first layer supported by the light generating region. The surface of the first layer may have a dielectric function that varies spatially according to a pattern. The pattern may be configured so that light that emerges from the device via the surface of the first layer is more collimated than a Lambertian distribution of light.

Claims

1. A light-emitting diode comprising:

a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region,

wherein;

the first layer comprises a semiconductor material and a surface of the first layer is configured so that light generated by the light generating region can emerge from the light-emitting diode via the surface of the first layer;

the surface of the first layer has a dielectric function that varies spatially according to a pattern, wherein the pattern is defined, at least in part, by a plurality of non-concentric holes; and

the pattern is configured so that light generated by the light-generating region that emerges from the light-emitting diode via the surface of the first layer is substantially incoherent and more collimated than a Lambertian distribution of light.

2. The light-emitting diode of claim 1, wherein, when light generated by the light-generating region emerges from the light-emitting diode via the surface of the first layer, at least about 40% of the light emerging via the surface of the first layer emerges within at most about 30°

of an angle normal to the surface of the first layer.

3. The light-emitting diode of claim 1, wherein the filling factor of the light-emitting diode is at least about 10%.

4. The light-emitting diode of claim 3, wherein the filling factor of the light-emitting diode is at most about 75%.

5. The light-emitting diode of claim 1, wherein the filling factor of the light-emitting diode is at most about 75%.

6. The light-emitting diode of claim 1, further comprising a support that supports the multi-layer stack of materials.

7. The light-emitting diode of claim 6, further comprising a layer of reflective material that is capable of reflecting at least about 50% of light generated by the light-generating region that impinges on the layer of reflective material, the layer of reflective material being between the support and the multi-layer stack of materials.

8. The light-emitting diode of claim 7, wherein the reflective material is a heat sink material.

9. The light-emitting diode of claim 8, wherein the heat sink material is configured so that the heat sink material has a vertical heat gradient during use of the light-emitting diode.

10. The light-emitting diode of claim 7, further comprising a heat sink material.

11. The light-emitting diode of claim 10, wherein the heat sink material is configured so that the heat sink material has a vertical heat gradient during use of the light-emitting diode.

12. The light-emitting diode of claim 1, further including a current-spreading layer between the first layer and the light-generating region.

13. The light-emitting diode of claim 1, further comprising electrical contacts configured to inject current into the light-emitting diode.

14. The light-emitting diode of claim 13, wherein the electrical contacts are configured to vertically inject electrical current into the light-emitting diode.

15. The light-emitting diode of claim 1, wherein the light-emitting diode is selected from the group consisting of OLEDs, flat surface-emitting LEDs, HBLEDs, and combinations thereof.

16. The light-emitting diode of claim 1, wherein the pattern does not extend into the light-generating region.

17. The light-emitting diode of claim 1, wherein the pattern does not extend beyond the first layer.

19. The light-emitting diode of claim 1, further comprising a layer of reflective material that is capable of reflecting at least about 50% of light generated by the light-generating region that impinges on the layer of reflective material,

wherein the light-generating region is between the layer of reflective material and the first layer.

20. The light-emitting diode of claim 1, wherein the pattern is a nonperiodic pattern or a complex periodic pattern.

24. The light-emitting diode of claim 1, wherein the surface of the first layer has features with a size of less than about λ

/5, where λ

is a wavelength of light that can be generated by the light-generating region and that can emerge from the light-emitting diode via the surface of the first layer.

26. The light-emitting diode of claim 1, wherein the dielectric function varies spatially according to a nonperiodic pattern.

27. The light-emitting diode of claim 1, wherein the dielectric function varies spatially according to a complex periodic pattern.

30. The light-emitting diode of claim 1, wherein the dielectric function varies spatially according to a periodic pattern.

32. The light-emitting diode of claim 1, wherein the surface of the first layer has holes with a size of less than about 90 nm.

38. The light-emitting diode of claim 26, wherein a majority of the nonperiodic pattern has order.

18. A light-emitting diode comprising:

a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region,

wherein;

the first layer comprises a semiconductor material and a surface of the first layer is configured so that light generated by the light generating region can emerge from the light-emitting diode via the surface of the first layer;

the surface of the first layer has a dielectric function that varies spatially according to a pattern, wherein the pattern is defined, at least in part, by a plurality of separate features; and

the pattern is configured so that light generated by the light-generating region that emerges from the light-emitting diode via the surface of the first layer is substantially incoherent and more collimated than a Lambertian distribution of light,

wherein the pattern extends beyond the first layer.

21. A wafer, comprising:

a plurality of light-emitting diodes, at least some of the light-emitting diodes comprising;

a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region, the first layer comprises a semiconductor material and a surface of the first layer is configured so that light generated by the light-generating region can emerge from the light-emitting diode via the surface of the first layer, the surface of the first layer having a dielectric function that varies spatially according to a pattern defined, at least in part, by a plurality of non-concentric holes, and the pattern being configured so that light generated by the light-generating region that emerges from the light-emitting diode via the surface of the first layer is substantially incoherent and more collimated than a Lambertian distribution of light,

wherein the wafer includes at least about five light-emitting diodes per square centimeter.

22. The wafer of claim 21, wherein the wafer includes at least about 25 light-emitting diodes per square centimeter.

23. The wafer of claim 21, wherein the wafer includes at least about 50 light-emitting diodes per square centimeter.

25. The wafer of claim 21, wherein the surface of the first layer has features with a size of less than about λ

/5, where λ

is a wavelength of light that can be generated by the light-generating region and that can emerge from the light-emitting diode via the surface of the first layer.

28. The wafer of claim 21, wherein, for the at least some of the light-emitting diodes, the dielectric function varies spatially according to a nonperiodic pattern.

29. The wafer of claim 21, wherein, for the at least some of the light-emitting diodes, the dielectric function varies spatially according to a complex periodic pattern.

31. The wafer of claim 25, wherein, for the at least some of the light-emitting diodes the dielectric function varies spatially according to a periodic pattern.

33. The wafer of claim 21, wherein the surface of the first layer has holes with a size of less than about 90 nm.

39. The wafer of claim 28, wherein a majority of the nonperiodic pattern has order.

34. A light-emitting diode comprising:

a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region,

wherein;

the first layer comprises a semiconductor material and a surface of the first layer is configured so that light generated by the light generating region can emerge from the light-emitting diode via the surface of the first layer;

the surface of the first layer has a dielectric function that varies spatially according to a pattern defined, at least in part, by a plurality of holes being devoid of material within a perimeter defined by the first layer; and

the pattern is configured so that light generated by the light-generating region that emerges from the light-emitting diode via the surface of the first layer is more collimated than a Lambertian distribution of light.

35. The light-emitting diode of claim 34, wherein the dielectric function varies spatially according to a nonperiodic pattern.

36. The light-emitting diode of claim 34, wherein, when light generated by the light-generating region emerges from the light-emitting diode via the surface of the first layer, at least about 40% of the light emerging via the surface of the first layer emerges within at most about 30°

of an angle normal to the surface of the first layer.

37. The light-emitting diode of claim 34, wherein the filling factor of the light-emitting diode is at least about 10%.

40. The light-emitting diode of claim 35, wherein a majority of the nonperiodic pattern has order.