μ-LED, μ-LED device, display and method for the same
The invention relates to various aspects of a μ-LED or a μ-LED array for augmented reality or lighting applications, in particular in the automotive field. The μ-LED is characterized by particularly small dimensions in the range of a few μm.
1. A μ-LED array with two adjacent light emitting devices arranged adjacent to each other and separated by a space in between, wherein each light emitting device comprises:
an n-doped layer;
a p-doped layer;
an active layer forming partly an active region, the active region located in between the n-doped layer and the p-doped layer;
a first insulating layer covering at least a side edge of the n-doped layer; and
a second insulating layer covering at least a side edge of the p-doped layer,
wherein the active layer extends across the space between the two adjacent light emitting devices,
wherein the active layer is covered by two or more cladding layers and forms a material transition layer with a maximum thickness dC along the space between the two adjacent light emitting devices, with the p-doped layer and the n-doped layer not extending along the space, whereby electrical and optical conductivities in the material transition layer are reduced.
2. The μ-LED array according to claim 1 , further comprising a filling material in the space between the two adjacent light emitting devices that is electrically isolated from material of the active layer.
3. The μ-LED array according claim 2 , wherein the filling material comprises:
a smaller band gap than the active region of the active layer and thus absorbing light of the active region, or
an increased refractive index greater than a refractive index of the n-doped layer or the p-doped layer of the two adjacent light emitting devices.
4. The μ-LED array according to claim 2 , wherein the filling material comprises an increased refractive index by diffusing or implanting a refractive index-increasing material into the filling material and into a respective cladding layer.
5. The μ-LED array according to claim 1 , further comprising at least one optical structure that comprises a photonic crystal and/or a Bragg mirror arranged on or generated in the active layer along the space between the two adjacent light emitting devices.
6. The μ-LED array according to claim 1 , further comprising two electrical contacts for generating an electrical field extending through two main surfaces of the active layer along the space between the two adjacent light emitting devices.
7. The μ-LED array according to claim 1 , wherein main surfaces of the active layer along the space between the two adjacent light emitting devices are covered by a respective passivation layer comprising silicon dioxide.
8. The μ-LED array according to claim 1 , further comprising a light-shaping structure, which is applied to a surface of the μ-LED array facing a main emission direction of the two adjacent light emitting devices, the light-shaping structure comprising a photonic structure.
9. The μ-LED array according to claim 8 , wherein the light-shaping structure extends into one of the n-doped layer and the p-doped layer of the two adjacent light emitting devices.
10. The μ-LED array according to claim 8 , wherein portions of the light-shaping structure are filled with a converter material.
11. The μ-LED array according to claim 1 , wherein the first and second insulating layers extend on respective main surfaces of the active layer along the space between the two adjacent light emitting devices.