Method of fabricating semiconductor light emitting device substrate

Abstract

A method of fabricating a substrate for semiconductor light emitting devices is provided. The method includes forming a nanocrystal structure on a surface of the substrate which is a single crystal material, wherein the nanocrystal structure has an etched region and an unetched region. Next, a nitride semiconductor material is grown on the surface of the single crystal material with an epitaxial process, so as to form a substrate. Due to the periodicity of the nanocrystal structure, the semiconductor material grown on the substrate has fewer defects, and the material stress is reduced. Besides, the nanocrystal structure is capable of diffracting an electromagnetic wave, such that a higher light emitting efficiency and a higher output power may be obtained accordingly.

1 . A method of fabricating a semiconductor light emitting device substrate, comprising:
 preparing a single crystal material;   forming a nanocrystal structure on a surface of the single crystal material, the nanocrystal structure having an etched region and an unetched region, wherein the etched region has a depth of 10-200 nm, and   growing a nitride semiconductor material on a surface of the single crystal material by performing an epitaxial process to form a substrate.   
   
   
       2 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein a material of the substrate is transmissive and does not absorb light in the wavelength range of visible light and infrared light. 
   
   
       3 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein the single crystal material comprises Al 2 O 3 , LiAlO 2 , LiGaO 2 , SiC, GaN, AlN, or AlGaN. 
   
   
       4 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein the step of forming the nanocrystal structure comprises:
 defining a pattern on the surface of the single crystal material by performing a lithographic process; and   performing an etching process on the surface of the single crystal material to form the nanocrystal structure.   
   
   
       5 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 4 , wherein the etching process comprises dry etching or wet etching. 
   
   
       6 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 4 , wherein the lithographic process comprises laser interference lithography, holography-lithography, E-beam lithography, X-ray lithography, nano lithography, or nano imprinting. 
   
   
       7 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 4 , wherein the pattern is a periodically arranged geometric pattern, the periodic structure has a plurality of crystals with a size of 100-900 nm, and each of the crystals has a quadrilateral-shape, a pentagon-shape, a hexagon-shape, or a polygon-shape. 
   
   
       8 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein the geometric pattern comprises at least a periodic pattern of tetragonal lattice or hexagonal lattice. 
   
   
       9 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein the epitaxial process comprises MBE, MOCVD, OMVPE, HVPE, PECVD, or sputter. 
   
   
       10 . The method of fabricating the semiconductor light emitting device substrate as claimed in  claim 1 , wherein the nitride semiconductor material comprises In, Al, or Ga.