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 arrangement, comprising:
a substrate with surrounding frame having bevelled sidewalls; and
three μ-LED chips arranged within the frame on the substrate, each of the three μ-LED chips comprising an emission surface with a first electrical contact on a side facing away from the substrate;
a mirror coating on the bevelled sidewalls and a top portion of the surrounding frame electrically connected to an electrical control contact on a surface of the substrate, an emission side of the three μ-LED chips opposite the substrate uncovered by the mirror coating; and
a common transparent conductive cover arranged on the emission surfaces and connecting the respective first electrical contacts to the mirror coating on the top portion of the surrounding frame.
2 . The μ-LED arrangement according to claim 1 , further comprising:
a transparent cover electrode, which extends over the electrical control contact and connects it to the mirror coating, the mirror coating being arranged at least partially below the transparent cover electrode and spaced therefrom.
3 . The μ-LED arrangement according to claim 2 , wherein:
the transparent cover electrode has an electrically conductive oxide layer including a material comprising IGZO, metal oxides, zinc oxide, tin oxide, cadmium oxide, indium-doped tin oxide (ITO), aluminium-doped (AZO), Zn 2 SnO 4 , CdSnO 3 , ZnSnO 3 , In 4 Sn 3 O 12 or mixtures of different transparent conductive oxides.
4 . The μ-LED arrangement according to claim 2 , wherein:
the substrate comprises a border at least partially surrounding the three μ-LED chips, on an upper side of the border the mirror coating is arranged and is electrically connected to a surface of the transparent cover electrode.
5 . The μ-LED arrangement according to claim 1 , wherein:
the electrical control contact is not located below a transparent cover electrode, and the mirror coating in at least one area is not located below the transparent cover electrode.
6 . The μ-LED arrangement according to claim 1 , wherein:
the mirror coating comprises a metal mirror including at least one of the following metals: Al, Ag, AgPdCu, Nd, Nb, La, Au, Cu, Pd, Pt, Mg, Mo, Cr, Ni, Os, Sn, Zn and combinations of the above.
7 . The μ-LED arrangement according to claim 1 , wherein:
the substrate has a cavity in which the three μ-LED chips are disposed, the cavity having a depth substantially equal to a height of the three μ-LED chips.
8 . The μ-LED arrangement according to claim 1 , wherein:
an insulating planar isolation layer is provided around the three μ-LED chips and has a first height that is substantially less than or equal to a second height of the three μ-LED chips.
9 . The μ-LED arrangement according to claim 8 , wherein:
the insulating planar isolation layer, at least partially between the transparent cover electrode and the mirror coating, extends above the substrate between the three μ-LED chips and a surrounding border.
10 . The μ-LED arrangement according to claim 8 , further comprising:
an insulating planar isolation layer bevelled at a distance from the three μ-LED chips in at least one region and a transparent cover electrode extending in a direction of the mirror coating, wherein edges of a bevelled area adjacent the insulating planar isolation layer have a flat pitch angle.
11 . The μ-LED arrangement according to claim 1 , wherein:
direct electrical contact of the transparent cover electrode with the mirror coating is provided by a via or by the mirror coating through an insulating planar isolation layer.
12 . The μ-LED arrangement according to claim 1 , wherein:
the three μ-LED chips each has a second electrical contact directly connected to a contact on a surface of the substrate.
13 . A pixel with at least one μ-LED arrangement according to claim 1 , wherein:
a red, a green and a blue light-providing μ-LED chip is fixed on the substrate, the first electrical contacts of which are connected to a conductive reflective layer via a transparent conductive cover electrode.
14 . The pixel according to claim 13 , wherein:
the three μ-LED chips are surrounded by a common border or arranged in a common cavity.
15 . The pixel according to claim 13 , wherein:
areas on the substrate between the three μ-LED chips are at least partially covered with a reflective layer including the mirror coating.
16 . The pixel according to claim 13 , wherein:
the three μ-LED chips are embedded in a transparent and non-conductive material.
17 . The pixel according to claim 13 , wherein:
the substrate comprises a plurality of leads configured to individually control each of the three μ-LED chips; or
the substrate comprises thin film transistor structures and electrical leads for an individual power supply to each μ-LED chip.
18 . The pixel according to claim 13 , further comprising:
a light-shaping patterned layer on or in the transparent conductive cover electrode, which comprises a lenticular element, a photonic crystal or a quasi-crystal structure and is adapted to suppress or reduce light emitted parallel to a surface of the substrate.
19 . The pixel according to claim 13 , wherein:
the transparent conductive cover electrode is structured to collimate and radiate light in a direction away from the surface of the substrate, or to couple out light.
20 . The pixel according to claim 13 , wherein:
a converter material for light conversion is arranged at least above and/or around one of the three μ-LED chips, wherein the converter material is electrically insulated from the transparent conductive cover electrode by an insulating layer.
21 . The pixel according to claim 13 , further comprising:
a raised area on the substrate surrounding the three μ-LED chips.
22 . A μ-display module with a plurality of pixels according to claim 13 , wherein the substrate comprises a plurality of cavities separated from one another, one of the plurality of pixels being located in each of the plurality of cavities.
23 . The μ-display module according to claim 22 , wherein:
a converter material for light conversion with quantum dots, is incorporated in at least some cavities of the plurality of cavities.
24 . The μ-display module according to claim 22 , wherein:
sidewalls of an elevation or the sidewalls between the plurality of cavities comprise a reflective layer, especially the mirror coating.
25 . The μ-display module according to claim 22 , wherein:
the substrate comprise conductive structures, which are configured to individually address and drive the plurality of pixels of the μ-display module.
26 . The μ-LED arrangement of claim 1 , wherein the a space between the three μ-LED chips and the bevelled sidewalls is filled with a transparent dielectric material.