Built-in bypass diode

Abstract

A bypass diode can include a first conductive region of a first conductivity type disposed above a substrate of a solar cell and a second conductive region of a second conductivity type disposed above the first conductive region. The bypass diode can include a thin dielectric region disposed directly between the first and second conductive regions.

What is claimed is: 
     
         1 . A method of fabricating a bypass diode for a solar cell, the method comprising:
 forming a first conductive region of a first conductivity type on a first dielectric layer on a substrate of the solar cell;   forming a second dielectric layer on the first conductive region;   removing a portion of the second dielectric layer;   forming a second conductive region of a second conductivity type above a portion of the first conductive region exposed by the removed portion of the second dielectric layer;   removing a portion of the second conductive region to separate the second conductive region into first and second portions of the second conductive region; and   coupling metal of the second conductivity type to the first conductive region and metal of the first conductivity type to the first portion of the second conductive region.   
     
     
         2 . The method of  claim 1 , wherein said forming the first conductive region includes forming a p-type conductive region, and wherein said forming the second conductive region includes forming an n-type conductive region, wherein said coupling includes coupling n-metal to the p-type conductive region and p-metal to the first portion of the n-type conductive region. 
     
     
         3 . The method of  claim 1 , wherein said removing a portion of the second conductive region includes laser ablating the portion of the second conductive region. 
     
     
         4 . The method of  claim 1 , further comprising prior to said forming the second conductive region, forming a third dielectric layer, wherein the third dielectric layer provides separation between the first and second conductive regions. 
     
     
         5 . The method of  claim 1 , wherein said removing the portion of the second dielectric layer includes laser ablating the portion of the second dielectric layer without removing a portion of the first conductive region below the ablated portion. 
     
     
         6 . A method of fabricating a bypass diode for a solar cell, the method comprising:
 forming an opening in a dielectric layer on a first conductive region;   forming a second conductive region above the first conductive region through the opening in the dielectric layer;   isolating a first portion of the second conductive region from a second portion of the second conductive region; and   forming a conductive connection between the first conductive region and its corresponding opposite metal type and between the second portion of the second conductive region and its corresponding opposite metal type.   
     
     
         7 . The method of  claim 6 , wherein said forming the opening in the dielectric layer is performed by laser ablation. 
     
     
         8 . The method of  claim 6 , wherein said isolating the first from the second portion of the second conductive region includes laser ablating the second conductive region. 
     
     
         9 . The method of  claim 6 , wherein said forming the conductive connection includes forming a conductive connection between an n-type conductive region and p-type metal and between a p-type conductive region and n-type metal. 
     
     
         10 . The method of  claim 6 , wherein said forming the opening in the dielectric layer includes forming the opening in a silicon dioxide layer on the first conductive region, wherein the first conductive region is a p-type conductive region. 
     
     
         11 . The method of  claim 6 , further comprising forming another dielectric layer before said forming the second conductive region wherein the other dielectric layer provides separation between the first and second conductive regions. 
     
     
         12 . The method of  claim 11 , wherein forming the other dielectric layer provides a lateral separation between the first and second conductive regions. 
     
     
         13 . The method of  claim 11 , wherein forming the other dielectric layer provides lateral and vertical separation between the first and second conductive regions. 
     
     
         14 . The method of  claim 6 , wherein said forming the second conductive region includes forming amorphous silicon above the first conductive region through the opening in the dielectric layer. 
     
     
         15 . The method of  claim 6 , wherein said forming the second conductive region includes forming n-type polysilicon on the first conductive region. 
     
     
         16 . A bypass diode for a solar cell, the bypass diode comprising:
 a first conductive region of a first conductivity type disposed above a substrate of the solar cell;   a second conductive region of a second conductivity type disposed above the first conductive region; and   a thin dielectric region disposed directly between the first and second conductive regions.   
     
     
         17 . The bypass diode of  claim 16 , wherein the thin dielectric region is disposed laterally directly between the first and second conductive regions without an isolation trench disposed in the substrate between the first and second conductive regions. 
     
     
         18 . The bypass diode of  claim 16 , wherein the thin dielectric region is disposed directly above the first conductive region and wherein the second conductive region is disposed directly above the thin dielectric region. 
     
     
         19 . The bypass diode of  claim 16 , wherein the thin dielectric region is a tunnel oxide. 
     
     
         20 . The bypass diode of  claim 16 , further comprising:
 a thin dielectric layer disposed on the substrate, wherein the first conductive region is disposed on the thin dielectric layer.