µ-LED, µ-LED DEVICE, DISPLAY AND METHOD FOR THE SAME

Abstract

Disclosed are 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 method for producing a μ-LED, comprising:
 creating an out-coupling structure in a surface region of a semiconductor body providing an active layer of the μ-LED by structuring a surface area by generating a random topology at the surface area; and 
 planarizing the surface area to obtain a planarized surface of the surface area; 
 wherein generating the random topology comprises layer-by-layer applying of a transparent second material having a high refractive index greater than 2 to the surface region and roughening the transparent second material. 
 
     
     
         2 . The method according to  claim 1 , wherein structuring the surface area comprises:
 roughening a surface of the surface region of the semiconductor body comprising a first material.   
     
     
         3 . The method according to  claim 2 ,
 wherein the transparent second material with the high refractive index comprises Nb 2 O 5 .   
     
     
         4 . The method according to  claim 1 , wherein planarizing comprises:
 applying, layer-by-layer, a transparent third material having a low refractive index less than 1.5 to the surface region.   
     
     
         5 . The method according to  claim 4 , further comprising:
 thinning the transparent third material of the low refractive index until a surface of the surface region terminates flat and/or smooth with highest elevations in a first material of the semiconductor body or in the transparent second material of the high refractive index.   
     
     
         6 . The method according to  claim 4 , wherein the transparent third material having the low refractive index comprises SiO 2  and is applied by TEOS (tetraethylorthosilicate). 
     
     
         7 . A μ-LED device, comprising:
 an out-coupling structure formed in a surface region of a semiconductor body providing the μ-LED device by structuring of the surface region; 
 wherein the surface region is planarized to obtain a planarized surface of the surface region; and 
 wherein the out-coupling structure comprises a transparent third material of low refractive index comprising SiO 2 , on a roughened transparent second material of high refractive index comprising Nb 2 O 5 , the roughened transparent second material being attached to a first material of the semiconductor body of the μ-LED device. 
 
     
     
         8 . The μ-LED device according to  claim 7 , wherein the surface region comprises a roughness less than 1 nanometre, as a mean roughness value. 
     
     
         9 . The μ-LED device according to  claim 7 , wherein the out-coupling structure comprises the transparent third material with the low refractive index comprising SiO 2 , on a roughened first material of the semiconductor body of the μ-LED device. 
     
     
         10 . The μ-LED device according to  claim 7 , wherein the out-coupling structure comprises the transparent third material of the low refractive index comprising SiO 2 , on a transparent second material of a high refractive index, the transparent second material being attached to the first material of the semiconductor body of the μ-LED device and comprising periodic photonic crystals or quasi-periodic or deterministic aperiodic photonic structures. 
     
     
         11 . A μ-LED arrangement for generating a pixel of a display, comprising:
 a flat carrier substrate; and 
 at least three μ-LEDs arranged on a mounting side of the flat carrier substrate, wherein the at least three μ-LEDs are adapted to emit light of different color transverse to a carrier substrate plane in a direction away from the flat carrier substrate; 
 a flat reflector element spatially arranged on an assembly side relative to the at least three μ-LEDs and configured to reflect light emitted by the at least three μ-LEDs in the direction of the flat carrier substrate; 
 wherein the flat carrier substrate is at least partially transparent so that light reflected from the flat reflector element propagates through the flat carrier substrate and emerges at a display side of the flat carrier substrate opposite the mounting side; 
 wherein a photonic structure is incorporated in or on the flat carrier substrate, with first and second regions with different refractive indexes, whereas converter material forms one of the first and second regions and is configured in such a way that radiation is emitted as a directed beam of rays.