Search

US-12622113-B2 - Light emitting device with improved radiation distribution and method of making thereof

US12622113B2US 12622113 B2US12622113 B2US 12622113B2US-12622113-B2

Abstract

A light emitting device includes a substrate, a plurality of light emitting diodes located over the substrate, and a plurality of micro-lenses. Each of the plurality of micro-lenses is located over a respective one of the plurality of light emitting diodes. Each of the plurality of micro-lenses has a first symmetry axis, each of the plurality of light emitting diodes has a second symmetry axis, and at least some of the plurality of micro-lenses have the first symmetry axis which is laterally displaced relative to the second symmetry axis of the respective one of the plurality of light emitting diodes.

Inventors

  • Brian Kim

Assignees

  • SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date
20260505
Application Date
20221122

Claims (17)

  1. 1 . A light emitting device, comprising: a substrate; a plurality of light emitting diodes located over the substrate; and a plurality of micro-lenses, wherein each of the plurality of micro-lenses is located over a respective one of the plurality of light emitting diodes, wherein each of the plurality of micro-lenses has a first symmetry axis, each of the plurality of light emitting diodes has a second symmetry axis, and at least some of the plurality of micro-lenses have the first symmetry axis which is laterally displaced relative to the second symmetry axis of the respective one of the plurality of light emitting diodes, wherein: the plurality of light emitting diodes is configured as an ordered array of pixels with each pixel comprising a red subpixel, a blue subpixel, and a green subpixel; the substrate includes electrical circuitry configured to control the plurality of light emitting diodes such that the light emitting device is configured as a display that generates an image; and a spatial extent of the image is determined by displacements of the plurality of micro-lenses relative to the respective light emitting diodes, and a displacement of each of the plurality of micro-lenses varies from lens to lens such that the light emitting device generates the image having a first size that is enlarged relative to a second size of the light emitting device.
  2. 2 . The light emitting device of claim 1 , wherein the plurality of light emitting diodes are arranged in a first array, the plurality of micro-lenses are arranged in a second array, and the first array has a smaller period than the second array in two orthogonal directions which are parallel to a top surface of the substrate.
  3. 3 . The light emitting device of claim 1 , wherein the plurality of light emitting diodes are arranged in a first array, the plurality of micro-lenses are arranged in a second array, and the first array has a larger period than the second array in two orthogonal directions which are parallel to a top surface of the substrate.
  4. 4 . The light emitting device of claim 1 , wherein the displacement of each of the plurality of micro-lenses has a common value such that the light emitting device generates the image that is directed at an angle relative to a direction perpendicular to a surface of the substrate on which the plurality of light emitting diodes is formed.
  5. 5 . The light emitting device of claim 4 , wherein the plurality of light emitting diodes are arranged in a first array, the plurality of micro-lenses are arranged in a second array, and the first array has a same period as the second array in two orthogonal directions which are parallel to a top surface of the substrate.
  6. 6 . The light emitting device of claim 5 , wherein all the plurality of micro-lenses have the first symmetry axis which is laterally displaced relative to the second symmetry axis of the respective one of the plurality of light emitting diodes.
  7. 7 . The light emitting device of claim 1 , further comprising: a plurality of optical cavities each bounded by a cavity wall, wherein each of the plurality of light emitting diodes is located in a respective optical cavity and is configured to emit blue or ultraviolet radiation incident photons; and a color conversion material located over each of the plurality of light emitting diodes that is configured to absorb the incident photons emitted by the light emitting diode and to generate converted photons having a longer peak wavelength than a peak wavelength of the incident photons.
  8. 8 . The light emitting device of claim 1 , wherein each of the plurality of micro-lenses is configured to receive photons generated by the respective one of the plurality of light emitting diodes, and to form a radiation pattern of the photons that is peaked in a predetermined direction that is determined based on a lateral displacement of the first symmetry axis of the micro-lens relative to the second symmetry axis of the respective one of the plurality of light emitting diodes.
  9. 9 . The light emitting device of claim 8 , wherein the predetermined direction varies in a first range from greater than 0 degrees to 30 degrees, relative to a direction of the first symmetry axis, as the first symmetry axis is laterally displaced relative to the second symmetry axis in a second range from greater than 0 microns to 1 micron.
  10. 10 . The light emitting device of claim 8 , wherein the predetermined direction varies as an approximately linear function of the displacement of the first symmetry axis relative to the second symmetry axis.
  11. 11 . The light emitting device of claim 1 , wherein a first diameter of each of the plurality of micro-lenses is approximately larger than a second diameter of a respective one of the plurality of light emitting diodes.
  12. 12 . The light emitting device of claim 11 , wherein the first diameter is 9 microns or less and the second diameter is 3 microns or less.
  13. 13 . The light emitting device of claim 11 , wherein all of the plurality of micro-lenses have a same diameter and a same height.
  14. 14 . The light emitting device of claim 1 , wherein the light emitting device comprises a display device.
  15. 15 . The light emitting device of claim 14 , wherein the display device comprises a virtual reality display device.
  16. 16 . The light emitting device of claim 14 , wherein the display device comprises an augmented reality display device.
  17. 17 . The light emitting device of claim 14 , wherein the display device comprises a heads up display device.

Description

FIELD This disclosure relates to light emitting devices, and particularly to light emitting diodes having micro-lenses that generate narrow angular radiation distributions and methods of fabricating the same. BACKGROUND Light emitting devices are used in electronic displays, such as backlights in liquid crystal displays in laptop computers and televisions. Light emitting devices include light emitting diodes (LEDs) and various other types of electronic devices configured to emit light. For light emitting devices, such as LEDs, the emission wavelength is determined by the band gap of the active region of the LED together with size dependent quantum confinement effects. Often the active region includes one or more bulk semiconductor layers or quantum wells (QW). For III-nitride based LED devices, such as GaN based devices, the active region (e.g., bulk semiconductor layer or QW layer) material may be ternary, having a composition such as InxGa1-xN, where 0<x<1. The band gap of such III-nitride materials is dependent on the amount of In incorporated in the active region. Higher indium incorporation yields a smaller band gap and thus longer wavelength of the emitted light. As used herein, the term “wavelength” refers to the peak emission wavelength of the LED. It should be understood that a typical emission spectra of a semiconductor LED is a narrow band of wavelengths centered around the peak wavelength. SUMMARY An embodiment light emitting device includes a substrate, a plurality of light emitting diodes located over the substrate, and a plurality of micro-lenses. Each of the plurality of micro-lenses is located over a respective one of the plurality of light emitting diodes. Each of the plurality of micro-lenses has a first symmetry axis, each of the plurality of light emitting diodes has a second symmetry axis, and at least some of the plurality of micro-lenses have the first symmetry axis which is laterally displaced relative to the second symmetry axis of the respective one of the plurality of light emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a vertical cross-sectional view of an intermediate structure that may be used in the formation of an array of light emitting devices, according to various embodiments. FIG. 1B is a vertical cross-sectional view of a further intermediate structure that may be used in the formation of an array of light emitting devices, according to various embodiments. FIG. 1C is a vertical cross-sectional view of a further intermediate structure that may be used in the formation of an array of light emitting devices, according to various embodiments. FIG. 1D is a vertical cross-sectional view of an array of light emitting devices, according to various embodiments. FIG. 1E is a vertical cross-sectional view of a further array of light emitting devices, according to various embodiments. FIG. 2A is a top perspective view of a first patterned matrix having a plurality of vias formed therein, according to various embodiments. FIG. 2B is a top perspective view of a second patterned matrix having a plurality of vias formed therein, according to various embodiments. FIG. 3 is a vertical cross-sectional view of a micro-LED that emits a Lambertian radiation pattern, according to various embodiments. FIG. 4 is a vertical cross-sectional view of a light emitting device that is configured to generate a Lambertian radiation pattern, according to various embodiments. FIG. 5 is a vertical cross-sectional view of a system in which a light emitting device having a Lambertian radiation pattern is coupled to an optical system, according to various embodiments. FIG. 6 is a vertical cross-sectional view of a system in which a light emitting device having a directional radiation pattern is coupled to an optical system, according to various embodiments. FIG. 7A is a vertical cross-sectional view of a system in which a light emitting device having a directional radiation pattern is coupled to an optical system, according to various embodiments. FIG. 7B is a vertical cross-sectional view of a further system in which a light emitting device having a directional radiation pattern is coupled to an optical system, according to various embodiments. FIG. 8A is a vertical cross-sectional view of a system in which a light emitting device having a first size is coupled to an optical system having a larger second size, according to various embodiments. FIG. 8B is a vertical cross-sectional view of a system in which a light emitting device having a first size is coupled to an optical system having a smaller second size, according to various embodiments. FIG. 9A is a vertical cross-sectional view of a system in which a light emitting device having a flat substrate is configured to generate a diverging radiation pattern, according to various embodiments. FIG. 9B is a vertical cross-sectional view of a system in which a light emitting device having a flat substrate is configured to generate a converging r