LED with active region disposed within an optical cavity defined by an embedded nanostructured layer and a reflector
This specification discloses LEDs in which the light emitting active region of the semiconductor diode structure is located within an optical cavity defined by a nanostructured layer embedded within the semiconductor diode structure on one side of the active region and a reflector located on the opposite side of the active region from the embedded nanostructured layer. The reflector may, for example, be a conventional specular reflector disposed on or adjacent to a surface of the semiconductor diode structure. Alternatively, the reflector may or comprise a nanostructured layer. The reflector may comprise a nanostructured layer and a specular reflector, with the nanostructured layer disposed adjacent to the specular reflector between the specular reflector and the active region.
1. A light emitting device comprising:
a semiconductor diode structure comprising an active region, a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces;
an array of nanoantennas embedded in the semiconductor diode structure between the active region and the top surface; and
a reflector located on the opposite side of the active region from the nanostructured layer,
the array of nanoantennas and the reflector forming an optical cavity that defines a plurality of cavity modes and a density of states, structures and positions of the nanoantennas and the reflector resulting in the cavity modes and density of states being tuned to achieve a selected level of internal quantum efficiency.
2. The light emitting device of claim 1 , wherein the reflector is located a distance from the active region less than or equal to a peak wavelength of light emitted by the active region in operation of the light emitting device.
3. The light emitting device of claim 1 , wherein the nanostructured layer is located a distance from the active region less than or equal to a peak wavelength of light emitted by the active region in operation of the light emitting device.
4. The light emitting device of claim 1 , wherein the nanostructured layer is located a distance from the active region greater than a peak wavelength of light emitted by the active region in operation of the light emitting device.
5. The light emitting device of claim 4 , wherein the nanostructured layer is located adjacent the top surface of the semiconductor diode structure.
6. The light emitting device of claim 1 , wherein the reflector is or comprises a specular reflector.
7. The light emitting device of claim 1 , wherein the reflector comprises a nanostructured reflector layer comprising an array of nanoantennas.
8. The light emitting device of claim 7 , wherein the nanoantennas are embedded in the bottom surface of the semiconductor diode structure.
9. The light emitting device of claim 7 , wherein the nanoantennas are disposed on the bottom surface of the semiconductor diode structure.
10. The light emitting device of claim 7 , wherein the nanoantennas are spaced apart from the bottom surface of the semiconductor diode structure.
11. The light emitting device of claim 1 , wherein the reflector comprises a specular reflector and a nanostructured reflector layer comprising an array of nanoantennas disposed between the specular reflector and the active region.
12. The light emitting device of claim 11 , wherein the nanoantennas are embedded in the bottom surface of the semiconductor diode structure.
13. The light emitting device of claim 12 , wherein the specular reflector is spaced apart from the nanoantennas.
14. The light emitting device of claim 12 , wherein the specular reflector is adjacent the nanoantennas.
15. The light emitting device of claim 11 , wherein the nanoantennas are disposed on the bottom surface of the semiconductor diode structure.
16. The light emitting device of claim 15 , wherein the specular reflector is spaced apart from the nanoantennas.
17. The light emitting device of claim 15 , wherein the specular reflector is adjacent the nanoantennas.
18. The light emitting device of claim 11 , wherein the nanoantennas are spaced apart from the bottom surface of the semiconductor diode structure.
19. The light emitting device of claim 18 , wherein the specular reflector is spaced apart from the nanoantennas.
20. The light emitting device of claim 18 , wherein the specular reflector is adjacent the nanoantennas.
21. The light emitting device of claim 1 , comprising:
a transparent substrate comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface of the transparent substrate disposed on or adjacent the top surface of the semiconductor diode structure; and
a nanostructured layer comprising an array of nanoantennas disposed on or adjacent the top surface of the transparent substrate.
22. The light emitting device of claim 21 , wherein the array of nanoantennas disposed on or adjacent the top surface of the transparent substrate is configured to collimate light emitted by the active region and incident on the top surface of the transparent substrate during operation of the light emitting device.
23. The light emitting device of claim 21 , wherein the array of nanoantennas disposed on or adjacent the top surface of the transparent substrate is configured to angularly filter light emitted by the active region and incident on the top surface of the transparent substrate during operation of the light emitting device.
24. The light emitting device of claim 21 , wherein the array of nanoantennas disposed on or adjacent the top surface of the transparent substrate is configured to reflect toward a side surface of the transparent substrate light that is incident on the top surface of the transparent substrate at or near normal incidence during operation of the light emitting device.
25. The light emitting device of claim 1 , comprising:
a transparent substrate comprising a top surface and an oppositely positioned bottom surface disposed with its bottom surface on or adjacent the top surface of the semiconductor diode structure; and
a nanostructured layer comprising an array of nanoantennas disposed at or adjacent an interface between the top surface of the semiconductor diode structure and the bottom surface of the transparent substrate.
26. The light emitting device of claim 25 , wherein the array of nanoantennas disposed at or adjacent the interface between the top surface of the semiconductor diode structure and the bottom surface of the transparent substrate is configured to reduce reflection of light emitted by the active region and incident on the interface during operation of the light emitting device.
27. The light emitting device of claim 25 , wherein the array of nanoantennas disposed at or adjacent the interface between the top surface of the semiconductor diode structure and the bottom surface of the transparent substrate is configured to collimate light emitted by the active region and incident on the interface during operation of the light emitting device.
28. A light emitting device, comprising:
a substrate; and
an array of LEDs arranged on the substrate, each LED comprising
a semiconductor diode structure comprising an active region, a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the substrate;
a nanostructured layer comprising an array of nanoantennas embedded in the semiconductor diode structure between the active region and the top surface; and
a reflector located on the opposite side of the active region from the nanostructured layer,
the array of nanoantennas and the reflector forming an optical cavity that defines a plurality of cavity modes and a density of states, structures and positions of the nanoantennas and the reflector resulting in the cavity modes and density of states being tuned to achieve a selected level of internal quantum efficiency.
29. The light emitting device of claim 28 , wherein the array of LEDs is a monolithic array of LEDs.
30. The light emitting device of claim 29 , wherein the LEDs are microLEDs.
31. The light emitting device of claim 30 , wherein a spacing between adjacent microLEDs is less than or equal to ten microns.