Light emitting diode

Abstract

A light emitting diode and a method for fabricating the same are provided. The light emitting diode includes: a transparent substrate; a semiconductor material layer formed on the top surface of a substrate with an active layer generating light; and a fluorescent layer formed on the back surface of the substrate with controlled varied thicknesses. The ratio of light whose wavelength is shifted while propagating through the fluorescent layer and the original light generated in the active layer can be controlled by adjusting the thickness of the fluorescent layer, to emit desirable homogeneous white light from the light emitting diode.

1 .- 20 . (canceled) 
     
     
         21 . A light emitting diode, comprising:
 a substrate;   a first compound semiconductor layer disposed on the substrate;   an active layer disposed on the first compound semiconductor layer;   a second compound semiconductor layer disposed on the active layer;   a first wavelength converting layer disposed on the substrate; and   a second wavelength converting layer disposed on a portion of a top surface of the first wavelength converting layer,   wherein a width of the second wavelength converting layer is less than a width of the first wavelength converting layer.   
     
     
         22 . The light emitting diode of  claim 21 , wherein the width of the second wavelength converting layer is less than a width of the active layer. 
     
     
         23 . The light emitting diode of  claim 21 , wherein the first wavelength converting layer covers the first compound semiconductor layer, the active layer and the second compound semiconductor layer. 
     
     
         24 . The light emitting diode of  claim 21 , wherein the top surface of the first wavelength converting layer is flat. 
     
     
         25 . The light emitting diode of  claim 21 , wherein a top surface of the second wavelength converting layer is flat. 
     
     
         26 . The light emitting diode of  claim 21 , wherein the second wavelength converting layer covers at least a central region of the first compound semiconductor layer. 
     
     
         27 . The light emitting diode of  claim 21 , wherein the second wavelength converting layer covers a region other than a central region of the first compound semiconductor layer. 
     
     
         28 . The light emitting diode of  claim 21 , further comprising:
 a first electrode electrically connected to the first compound semiconductor layer; and   a second electrode connected to the second compound semiconductor layer.   
     
     
         29 . A light emitting diode, comprising:
 a substrate;   a plurality of semiconductor stacks disposed on the substrate, each of the plurality of semiconductor stacks including a first compound semiconductor layer disposed on the substrate, an active layer disposed on the first compound semiconductor layer and a second compound semiconductor layer disposed on the active layer;   a first wavelength converting layer disposed on the substrate; and   a plurality of second wavelength converting layers disposed on the first wavelength converting layer,   wherein each of the plurality of second wavelength converting layers is disposed on or above a corresponding semiconductor stack among the plurality of semiconductor stacks.   
     
     
         30 . The light emitting diode of  claim 29 , wherein a width of each of the plurality of second wavelength converting layers is less than a width of the active layer. 
     
     
         31 . The light emitting diode of  claim 29 , wherein the first wavelength converting layer covers the plurality of semiconductor stacks. 
     
     
         32 . The light emitting diode of  claim 29 , further comprising:
 a first electrode electrically connected to the first compound semiconductor layer; and   a second electrode connected to the second compound semiconductor layer.   
     
     
         33 . The light emitting diode of  claim 29 , wherein the plurality of semiconductor stacks are disposed on a bottom surface of the substrate, and
 the first wavelength converting layer is disposed on a top surface of the substrate.   
     
     
         34 . The light emitting diode of  claim 29 , wherein the first compound semiconductor layer includes GaN-based III-V nitride. 
     
     
         35 . The light emitting diode of  claim 29 , wherein the first compound semiconductor layer is formed of the same maternal as the second compound semiconductor layer. 
     
     
         36 . The light emitting diode of  claim 29 , wherein the first compound semiconductor layer is an n-type doped or undoped GaN-based III-V nitride compound semiconductor layer, and
 the second compound semiconductor layer is a p-type doped GaN-based III-V nitride compound semiconductor layer.   
     
     
         37 . A light emitting diode comprising:
 a substrate;   a first compound semiconductor layer disposed on the substrate;   an active layer disposed on the first compound semiconductor layer and configured to emit blue light;   a second compound semiconductor layer disposed on the active layer;   a wavelength converting layer containing a fluorescent material;   a first electrode connected to the first compound semiconductor layer; and   a second electrode connected to the second compound semiconductor layer,   wherein mixed light propagates through the wavelength converting layer and turns to white light,   the mixed light includes first light converted by the wavelength converting layer, and second light only transmitted through the wavelength converting layer, and   the wavelength converting layer has a first portion and a second portion that have different wavelength conversion characteristics from each other.   
     
     
         38 . The light emitting diode of  claim 37 , wherein the second light is not converted by the wavelength converting layer. 
     
     
         39 . The light emitting diode of  claim 37 , wherein a thickness of the first portion is greater than a thickness of the second portion. 
     
     
         40 . The light emitting diode of  claim 39 , wherein the mixed light propagating through the first portion of the wavelength converting layer absorbs more fluorescent grains than the mixed light propagating through the second portion.