Back contact to film silicon on metal for photovoltaic cells

Abstract

Systems and Methods for back contact to film silicon on metal for photovoltaic cells are provided. In one embodiment, a method for creating a conductive pathway in a photovoltaic cell comprises: obtaining a layered photovoltaic device comprising: a metal substrate with a crystal orientation; a crystal semiconductor layer with the crystal orientation; and a heteroepitaxially grown buffer layer positioned between the substrate and the crystal semiconductor layer; and forming one or more conductive pathways between the crystal semiconductor layer and the metal substrate, the pathways being through at least a portion of the buffer layer.

What is claimed is: 
     
         1 . A method for creating a conductive pathway in a photovoltaic cell comprising:
 obtaining a layered photovoltaic device comprising:
 a metal substrate with a crystal orientation; 
 a crystal semiconductor layer with the crystal orientation; and 
 a heteroepitaxially grown buffer layer positioned between the substrate and the crystal semiconductor layer; and 
   forming one or more conductive pathways between the crystal semiconductor layer and the metal substrate, the pathways being through at least a portion of the buffer layer.   
     
     
         2 . The method of  claim 1  further comprising directing a laser beam on the crystal semiconductor layer, the laser in an operating spectrum such that the laser does not interfere with atomic placements crystal orientation of the crystal semiconductor layer, the laser being absorbed at the metal substrate to form the conductive pathway between the crystal semiconductor layer and the metal substrate, the pathway including material from the metal substrate. 
     
     
         3 . The method  claim 2  wherein the operating spectrum of the laser comprises wavelengths within the infra red portion of the electromagnetic spectrum. 
     
     
         4 . The method of  claim 1  further comprising directing a laser on the metal substrate, the laser drilling holes through the metal substrate and causing metal from the metal substrate to diffuse through the buffer layer to electrically couple the metal substrate and the crystal silicon layer. 
     
     
         5 . The method of  claim 1  further comprising:
 applying an etchant to a backside of the metal substrate, the etchant creating apertures through the metal substrate and the buffer layer; and 
 filling the apertures with an electrically conductive material to electrically couple the metal substrate and the crystal silicon layer. 
 
     
     
         6 . A method for creating a conductive pathway in a photovoltaic cell comprising:
 forming apertures in a buffer layer grown over a metal substrate, the metal substrate and the buffer layer having a common crystalline structure; and   heteroepitaxially growing a crystal semiconductor layer after forming the apertures in the buffer layer, the apertures being filled with crystal semiconductor to form a conductive pathway in the buffer layer between the crystal semiconductor layer and the metal substrate.   
     
     
         7 . The method of  claim 6  further comprising:
 creating structures on the metal substrate prior to heteroepitaxially growing the buffer layer; and 
 removing the structures to form the apertures in the buffer layer. 
 
     
     
         8 . The method of  claim 6  further comprising:
 applying nanoparticles to the metal substrate prior to heteroepitaxially growing the buffer layer over the nanoparticles; and 
 mechanically or chemically removing the nanoparticles to form the apertures, wherein heteroepitaxially growing the crystal semiconductor fills the apertures to create vias electrically coupling the metal substrate and the crystal semiconductor layer. 
 
     
     
         9 . The method of  claim 6  further comprising:
 providing a mask over an edge of the metal substrate prior to heteroepitaxially growing the buffer layer; and 
 removing the mask after growing the buffer layer to form the apertures, wherein heteroepitaxially growing the crystal semiconductor fills the apertures to create vias electrically coupling the metal substrate and the crystal silicon layer. 
 
     
     
         10 . The method of  claim 6  further comprising:
 applying etchant to the buffer layer; and
 allowing the etchant to form the apertures in the buffer layer, wherein heteroepitaxially growing the crystal semiconductor fills the apertures to create vias electrically coupling the metal substrate and the crystal silicon layer. 
 
 
     
     
         11 . The method of  claim 10  wherein the etchant is applied in the form of droplets by an inkjet printer to form a grid array pattern, wherein the droplets are spaced on the buffer layer. 
     
     
         12 . The method of  claim 10  wherein the etchant is applied by spraying a fine mist of etchant onto the buffer layer to form a random pattern. 
     
     
         13 . The method of  claim 6  further comprising directing a laser at the buffer layer to form the apertures in the buffer layer, wherein heteroepitaxially growing the crystal semiconductor fills the apertures to create vias electrically coupling the metal substrate and the crystal semiconductor layer.