Light emitting devices with improved extraction efficiency
Light-emitting devices, and related components, systems and methods are disclosed.
1. A light-emitting device, comprising:
a multi-layer stack of materials including a layer of n-doped material, a layer of p-doped material, and a light-generating region; and
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:
a surface of the layer of n-doped material is configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the layer of n-doped material;
the surface of the layer of n-doped material has a dielectric function that varies spatially according to a pattern,
the pattern is configured so that light emitted by the surface of the layer of n-doped material has a spectrum of radiation modes, and the spectrum of radiation modes is substantially the same as a characteristic emission spectrum of the light-generating region:
a distance between the layer of p-doped material and the layer of reflective material is less than a distance between the layer of n-doped material and the layer of reflective material; and
the layer of n-doped material is supported by the layer of p-doped material.
2. The light-emitting device of claim 1 , wherein the multi-layer stack of materials comprises a multi-layer stack of semiconductor materials.
3. The light-emitting device of claim 1 , wherein the n-doped material comprises an n-doped semiconductor material and the p-doped material comprises a p-doped semiconductor material.
4. The light-emitting device of claim 1 , wherein the light-generating region is between the layer of n-doped material and the layer of p-doped semiconductor material.
5. The light-emitting device of claim 1 , further comprising a support that supports the multi-layer stack of materials.
6. The light-emitting device of claim 1 , further comprising a p-ohmic contact layer between the layer of p-doped material and the layer of reflective material.
7. The light-emitting device of claim 1 , further including a current-spreading layer between the layer of n-doped material and the light-generating region.
8. The light-emitting device of claim 1 , wherein the multi-layer stack of materials comprise semiconductor materials.
9. The light-emitting device of claim 8 , wherein the semiconductor materials are selected from the group consisting of III–V semiconductor materials, organic semiconductor materials and silicon.
10. The light-emitting device of claim 1 , wherein the surface of the layer of n-doped material has a dielectric function that varies spatially according to a pattern.
11. The light-emitting device of claim 10 , wherein the pattern does not extend into the light-generating region.
12. The light-emitting device of claim 10 , wherein the pattern does not extend beyond the layer of n-doped material.
13. The light-emitting device of claim 10 , wherein the pattern extends beyond the layer of n-doped material.
14. The light-emitting device of claim 10 , wherein the pattern is partially formed of a component selected from the group consisting of holes in the surface of the layer of n-doped material, pillars in the layer of n-doped material, continuous veins in the layer of n-doped material, discontinuous veins in the layer of n-doped material and combinations thereof.
15. The light-emitting device of claim 10 , wherein the pattern of variation is selected from the group consisting of nonperiodic patterns, complex periodic patterns, and patterns having an ideal lattice constant and a detuning parameter greater than zero.
16. The light-emitting device of claim 10 , wherein the pattern is partially formed of holes in the layer of n-doped material.
17. The light-emitting device of claim 10 , wherein the pattern is configured so that light emitted by the surface of the layer of n-doped material has a spectrum of radiation modes, and the spectrum of radiation modes is substantially the same as a characteristic emission spectrum of the light-generating region.
18. The light-emitting device of claim 10 , wherein the pattern does extends into the light-generating region.
19. The light-emitting device of claim 1 , further comprising electrical contacts configured to inject current into the light-emitting device.
20. The light-emitting device of claim 19 , wherein the electrical contacts are configured to vertically inject electrical current into the light-emitting device.
21. The light-emitting device of claim 1 , wherein the light-emitting device is selected from the group consisting of light-emitting diodes, lasers, optical amplifiers, and combinations thereof.
22. The light-emitting device of claim 1 , wherein the light-emitting device comprises a light emitting diode.
23. The light-emitting device of claim 1 , wherein the light-emitting device is selected from the group consisting of OLEDs, flat surface-emitting LEDs, HBLEDs, and combinations thereof.
24. The light-emitting device of claim 1 , wherein the surface of the layer of n-doped material is a roughened surface.
25. The light-emitting device of claim 24 , wherein the roughened surface is a locally non-planar interface.
26. The light-emitting device of claim 1 , wherein the surface of the layer of n-doped material is approximately smooth.
27. The light-emitting device of claim 1 , wherein the surface of the layer of n-doped material has a surface smoothness of less than about 5 nm root mean square (rms).
28. A light-emitting device, comprising:
a multi-layer stack of materials including a layer of n-doped material, a layer of p-doped material, and a light-generating region; and
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:
a surface of the layer of n-doped material is configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the layer of n-doped material,
the surface of the layer of n-doped material has a dielectric function that varies spatially according to a pattern,
the pattern is a nonperiodic pattern,
a distance between the layer of p-doped material and the layer of reflective material is less than a distance between the layer of n-doped material and the layer of reflective material; and
the layer of n-doped material is supported by the layer of p-doped material.
29. The light emitting device of claim 28 , wherein the pattern is partially formed of holes in the layer of n-doped material.
30. A light-emitting device, comprising:
a multi-layer stack of materials including a layer of n-doped material, a layer of p-doped material, and a light-generating region; and
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:
a surface of the layer of n-doped material is configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the layer of n-doped material;
a distance between the layer of p-doped material and the layer of reflective material is less than a distance between the layer of n-doped material and the layer of reflective material;
the layer of n-doped material is supported by the layer of p-doped material; and
the surface of the layer of n-doped material has a surface smoothness of less than about 5 nm root mean square (rms).
31. The light emitting device of claim 30 , wherein the surface of the layer of n-doped material has a dielectric function that varies spatially according to a pattern.
32. The light emitting device of claim 31 , wherein the pattern is partially formed of holes in the layer of n-doped material.