VCSEL Including A Self-Aligned, Deep Hole Evaporated Metal Contact

Abstract

A vertical cavity surface emitting laser (VCSEL) including a first ohmic contact to the substrate formed on an upper surface of the device, instead of the conventional substrate bottom-side contact. The VCSEL is formed to include a hole made through the first distributed Bragg reflector (DBR) and into the material of the substrate itself. A metal layer is deposited at the bottom of the hole to contact the substrate, where the deposited metal layer creates a high quality ohmic contact by not also contacting the inner sidewalls of the hole (i.e., no “stringers” are formed within the hole).

What is claimed is: 
     
         1 . A vertical cavity surface emitting layer (VCSEL) comprising:
 a substrate having first and second major surfaces;   a first distributed Bragg reflector (DBR) disposed on the first major surface of the substrate;   an active region disposed on a top surface of the first DBR;   a second DBR disposed over the active region;   a hole that extends through at least the first DBR and into the substrate, where a bottom surface of the hole exposes a portion of the substrate;   a first metal layer formed to cover a major extent of the bottom surface of the hole, the coverage of the first metal layer sufficient to form a first ohmic contact with the substrate;   a first electrically conductive material extending through the hole to make electrical contact between the first metal layer and the first DBR; and   a second ohmic contact coupled to the second DBR.   
     
     
         2 . The VCSEL of  claim 1  wherein the active region and the second DBR have a lateral extension that is less than that of the first DBR, exposing a portion of the top surface of the first DBR, with the hole formed in the exposed portion of the first DBR. 
     
     
         3 . The VCSEL of  claim 2  wherein the active region and the second DBR comprise a mesa geometry. 
     
     
         4 . The VCSEL of  claim 1  further comprising an aperture disposed between the active region and the second DBR. 
     
     
         5 . The VCSEL of  claim 4  wherein the aperture confines current flow in the VCSEL. 
     
     
         6 . The VCSEL of  claim 1  wherein the first DBR comprises a plurality of epitaxially grown layers. 
     
     
         7 . The VCSEL of  claim 1  wherein the first metal layer does not overlap with a sidewall of the hole. 
     
     
         8 . The VCSEL of  claim 1  wherein the VCSEL further comprises an insulating layer disposed between the first electrically conductive material and the first DBR. 
     
     
         9 . The VCSEL of  claim 8  where the insulating layer is disposed vertically along an inner wall of the hole from the first metal layer to a contact area on the first DBR.