Shallow junction photovoltaic devices

Abstract

A method for fabricating a photovoltaic device includes forming a first contact on a crystalline substrate, by epitaxially growing a first doped layer having a doping concentration of 10 19 cm −3 or greater, a dislocation density of 10 5 cm −2 or smaller, a hydrogen content of 0.1 atomic percent or smaller, and a thickness configured to reduce Auger recombination in the epitaxially grown doped layer. A first passivation layer is formed on the first doped layer. A second contact is formed on the crystalline substrate on a side opposite the first contact by epitaxially growing a second doped layer having a doping concentration of 10 19 cm −3 or greater, a dislocation density of 10 5 cm −2 or smaller, a hydrogen content of 0.1 atomic percent or smaller and a thickness configured to reduce Auger recombination in the second epitaxially grown doped layer. A second passivation layer is formed on the second doped layer.

What is claimed is: 
     
         1 . A photovoltaic device, comprising:
 a first contact formed on a crystalline substrate, the first contact including:
 a first doped crystalline layer having a doping concentration of 10 19  cm −3  or greater, a dislocation density of 10 5  cm −2  or smaller, a hydrogen content of 0.1 atomic percent or smaller, and a thickness configured to reduce Auger recombination in the first epitaxially grown doped layer; and 
 a first passivation layer formed on the first doped layer. 
   
     
     
         2 . The device as recited in  claim 1  further comprising a second contact formed on a surface of the crystalline substrate that is separate from a surface of the crystalline substrate that the first contact is formed on. 
     
     
         3 . The device as recited in  claim 2 , wherein the second contact includes a second crystalline doped layer having a doping concentration of 10 19  cm −3  or greater. 
     
     
         4 . The device as recited in  claim 3 , wherein the second crystalline doped layer of the second contact comprises a dislocation density of 10 5  cm −2  or smaller, and a hydrogen content of 0.1 atomic percent or smaller. 
     
     
         5 . The device as recited in  claim 4 , wherein the second crystalline doped layer comprises a thickness configured to reduce Auger recombination. 
     
     
         6 . The device as recited in  claim 2  further comprising a second passivation layer formed on the second crystalline doped layer. 
     
     
         7 . The device as recited in  claim 1 , wherein the crystalline substrate includes a dopant type and the first contact includes a same dopant type as the substrate and the second contact includes an opposite dopant type from the substrate. 
     
     
         8 . The device as recited in  claim 6 , further comprising a transparent conductor formed over the first and second passivation layers. 
     
     
         9 . The device as recited in  claim 1 , wherein the first doped layer includes a thickness of less than 10 nm. 
     
     
         10 . The device as recited in  claim 3 , wherein the second crystalline doped layer includes a thickness of less than 10 nm. 
     
     
         11 . The device as recited in  claim 1 , wherein the first passivation layer includes a thickness of less than 15 nm. 
     
     
         12 . The device as recited in  claim 6 , wherein the second passivation layer includes a thickness of less than 15 nm. 
     
     
         13 . The device as recited in  claim 2 , wherein the first contact and the second contact are integrated and alternate positions on a same side of the substrate to form an interdigitated back contact. 
     
     
         14 . The device as recited in  claim 6 , wherein the first passivation layer and the second passivation layer include a same intrinsic layer. 
     
     
         15 . The device as recited in  claim 6 , wherein the first passivation layer and the second passivation layer include a same dopant type as the crystalline doped layer in contact therewith. 
     
     
         16 . The device as recited in  claim 13 , further comprising:
 a front surface field structure formed on the substrate opposite the interdigitated back contact and including an epitaxially grown doped layer having a doping concentration of 10 19  cm −3  or greater, a dislocation density of 10 5  cm −2  or smaller, a hydrogen content of 0.1 atomic percent or smaller, and a thickness configured to reduce Auger recombination in the epitaxially grown doped layer; and   a passivation layer formed over the epitaxially grown doped layer.   
     
     
         17 . A photovoltaic device, comprising:
 a first contact formed on a crystalline substrate, the first contact including:
 a first doped crystalline layer having a doping concentration of 10 19  cm −3  or greater, a dislocation density of 10 5  cm −2  or smaller, a hydrogen content of 0.1 atomic percent or smaller, and a thickness configured to reduce Auger recombination in the first epitaxially grown doped layer; and 
 a first passivation layer formed on the first doped layer; and 
   a second contact formed on the crystalline substrate, the second contact including:
 a second crystalline doped layer having a dislocation density of 10 5  cm −2  or smaller; and 
 a second passivation layer formed on the second doped layer. 
   
     
     
         18 . The device of  claim 17 , wherein the doping concentration in the second crystalline doped layer is 10 19  cm −3  or greater. 
     
     
         19 . The device of  claim 17 , wherein the second crystalline doped layer has a hydrogen content of 0.1 atomic percent or smaller. 
     
     
         20 . The device of  claim 17 , wherein the second crystalline doped layer has a thickness configured to reduce Auger recombination.