Micron-sized light emitting diode designs

Abstract

A emitting diode (LED) includes an epitaxial structure defining a base and a mesa on the base. The base defines a light emitting surface of the LED and includes current spreading layer. The mesa includes a thick confinement layer, a light generation area on the thick confinement layer to emit light, a thin confinement layer on the light generation area, and a contact layer on the thin confinement layer, the contact layer defining a top of the mesa. A reflective contact is on the contact layer to reflect a portion of the light emitted from the light generation area, the reflected light being collimated at the mesa and directed through the base to the light emitting surface. In some embodiments, the epitaxial structure grown on a non-transparent substrate. The substrate is removed, or used to form an extended reflector to collimate light.

1 . A light emitting diode (LED), comprising:
 a mesa including a light generation area configured to generate light; and   a base below the mesa, the base including:
 a first side of the base for emitting the light, and 
 a second side of the base opposite the first side, the mesa on the second side; 
   a substrate with an aperture below the mesa, the light passing through the first side and transmitted through the aperture; and   a reflective contact on the mesa.   
     
     
         2 . The LED of  claim 1 , wherein the mesa and the base are parts of an epitaxial structure on the substrate. 
     
     
         3 . The LED of  claim 2 , further comprising a contact on the base, the contact in conjunction with the reflective contact providing electric current to the light generation area. 
     
     
         4 . The LED of  claim 1 , wherein the base comprises a first etch stop layer adjacent to the substrate, a current spread layer on the first etch stop layer, and a second etch stop layer on the current spreading layer, the mesa mounted on the second etch stop layer. 
     
     
         5 . The LED of  claim 1 , further comprising a reflector in the aperture to collimate the light. 
     
     
         6 . The LED of  claim 5 , wherein the reflector comprises silicon nitride, silicon oxide or metal. 
     
     
         7 . The LED of  claim 5 , wherein the reflector has a parabolic or included shape. 
     
     
         8 . The LED of  claim 1 , further comprising a dielectric layer between the reflective contact and the mesa. 
     
     
         9 . The LED of  claim 1 , wherein the substrate is made of a non-transparent material. 
     
     
         10 . The LED of  claim 9 , wherein the non-transparent material comprises gallium arsenide. 
     
     
         11 . A method of manufacturing a light emitting diode (LED), comprising:
 forming a mesa by etching a portion of an epitaxial structure, the mesa including a light generation area configured to generate light;   forming a reflective contact on the mesa, the reflective contact configured to reflect back a portion of the light; and   removing a portion of a substrate in the epitaxial structure to form an aperture through which the light is transmitted.   
     
     
         12 . The method of  claim 11 , further comprising thinning the substrate before forming the aperture. 
     
     
         13 . The method of  claim 11 , wherein the substrate is made of a non-transparent material. 
     
     
         14 . The method of  claim 13 , wherein the non-transparent material comprises gallium arsenide. 
     
     
         15 . The method of  claim 11 , wherein removing the portion of the substrate comprises performing etching on the substrate. 
     
     
         16 . The method of  claim 11 , further comprising forming a reflector in the aperture, the reflector configured to collimate the light transmitted through the aperture. 
     
     
         17 . The method of  claim 16 , wherein the reflector comprises silicon nitride, silicon oxide or metal. 
     
     
         18 . A method of operating a light emitting diode (LED), comprising:
 providing current to a light generation area of a mesa;   generating light from the light generation area of the mesa responsive to receiving the current;   reflecting a portion of the light by a reflective contact back towards an aperture in a substrate of a base under the mesa; and   emitting the reflected portion of the light and remaining portion of the light through the aperture.   
     
     
         19 . The method of  claim 18 , wherein the substrate comprises gallium arsenide. 
     
     
         20 . The method of  claim 18 , further comprising reflecting the light by a reflector in the aperture to collimate the light.