High-Efficiency Thin-Film Solar Cells

Abstract

A three-dimensional solar cell comprising a semiconductor substrate with an inverted pyramidal cavity, emitter metallization regions on ridges on the surface of the semiconductor substrate which define an opening of the inverted pyramidal cavity, and base metallization regions on a region which form the apex of the inverted pyramidal cavity. A method for fabricating a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate by doping ridges on the surface of the semiconductor substrate which define an opening of an inverted pyramidal cavity on the substrate to form an emitter region, and doping a region which forms the apex of the inverted pyramidal cavity to form a base region. Adding a surface passivation layer to the surface of the substrate. Selectively etching the passivation layer from the emitter region and base region. Then concurrently metallizing the emitter region and base region.

What is claimed is: 
     
         1 . A three-dimensional solar cell, comprising:
 a plurality of ridges on the surface of a semiconductor substrate defining an opening of an inverted pyramidal cavity;   a plurality of walls defining said inverted pyramidal cavity;   emitter metallization regions on said ridges forming the opening of said inverted pyramidal cavity; and   base metallization regions on a region forming an apex of said inverted pyramidal cavity.   
     
     
         2 . The solar cell of  claim 1 , wherein said semiconductor substrate is a mono-crystalline silicon substrate. 
     
     
         3 . The solar cell of  claim 1 , wherein said base metallization regions are mounted on a metal surface of a carrier plate to form base interconnects. 
     
     
         4 . The solar cell of  claim 1 , wherein a diagonal dimension defining said base opening of said inverted pyramidal cavity is in the range of 1 um to 1 mm. 
     
     
         5 . The solar cell of  claim 1 , wherein said semiconductor substrate comprises a plurality of said inverted pyramidal cavities. 
     
     
         6 . The solar cell of  claim 5 , wherein said plurality of said inverted pyramidal cavities have a plurality of pyramidal shapes. 
     
     
         7 . The solar cell of  claim 5 , wherein said plurality of said inverted pyramidal cavities have a plurality of pyramidal sizes. 
     
     
         8 . The solar cell of  claim 5 , wherein said ridges forming the opening of each of said inverted pyramidal cavities have a width ranging from 10 um to 100 um. 
     
     
         9 . The solar cell of  claim 5 , wherein said apex of said inverted pyramidal cavities further is substantially planar. 
     
     
         10 . The solar cell of  claim 5 , wherein said plurality of said inverted pyramidal cavities are arranged in arrays on the silicon substrate. 
     
     
         11 . The solar cell of  claim 5 , wherein said plurality of said inverted pyramidal cavities are arranged in a staggered pattern on the silicon substrate. 
     
     
         12 . The solar cell of  claim 5 , wherein said plurality of said inverted pyramidal cavities comprise:
 a first plurality of inverted pyramidal cavities; and   a second plurality of inverted pyramidal cavities,   wherein a diagonal dimension defining said base opening of said second plurality of inverted pyramidal cavities is smaller than a diagonal dimension defining said base opening of said first plurality of inverted pyramidal cavities.   
     
     
         13 . The solar cell of  claim 12 , wherein said plurality of said inverted pyramidal cavities are arranged in a staggered pattern on the silicon substrate. 
     
     
         14 . The solar cell of  claim 12 , wherein said apex of said inverted pyramidal cavities of said first plurality of inverted pyramidal cavities is substantially planar. 
     
     
         15 . A method for fabrication of a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate, the method comprising:
 doping ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a n-type dopant to form an emitter region;   doping a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a p-type dopant to form a base region;   adding a surface passivation layer to said first side and said second side of said silicon substrate;   selectively etching said passivation layer on said emitter region and said base region to form contact openings; and   concurrently metallizing said emitter region and said base region.   
     
     
         16 . The method of  claim 15 , wherein said step of doping ridges forming an opening of an inverted pyramidal cavity further comprises:
 selectively coating ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a n-type dopant; and   forming an emitter region on said ridges forming an opening according to a thermal annealing process.   
     
     
         17 . The method of  claim 15 , wherein said step of doping a region forming an apex of said inverted pyramidal cavity further comprises:
 selectively coating a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a p-type dopant; and   forming a base region on said region forming an apex according to a thermal annealing process.   
     
     
         18 . The method of  claim 15 , wherein said step of adding a surface passivation layer to said first side and said second side of said silicon substrate comprises adding a thermally grown silicon dioxide. 
     
     
         19 . The method of  claim 15 , further comprising the step of mounting said base region onto a metal surface of a carrier plate to form metal base interconnects. 
     
     
         20 . A method for fabrication of a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate, the method comprising:
 doping ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a p-type dopant to form a base region;   doping a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a n-type dopant to form an emitter region;   adding a surface passivation layer to said first side and said second side of said silicon substrate;   selectively etching said passivation layer on said emitter region and said base region to form contact openings; and   concurrently metallizing said emitter region and said base region.