Lattice matchable alloy for solar cells

Abstract

An alloy composition for a subcell of a solar cell is provided that has a bandgap of at least 0.9 eV, namely, Ga 1-x In x N y As 1-y-z Sb z with a low antimony (Sb) content and with enhanced indium (In) content and enhanced nitrogen (N) content, achieving substantial lattice matching to GaAs and Ge substrates and providing both high short circuit currents and high open circuit voltages in GaInNAsSb subcells for multijunction solar cells. The composition ranges for Ga 1-x In x N y As 1-y-z Sb z are 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03.

1 . An alloy composition suitable for substantial lattice matching to a substrate comprising:
 Ga 1-x In x As 1-y-z Sb z , with a low antimony (Sb) content and an enhanced indium (In) content and enhanced nitrogen (N) content for use in a selected subcell of a multijunction solar cell, to achieve a bandgap of at least 0.9 eV.   
     
     
         2 . The composition according to  claim 1 , the adjacent substrate being selected from the group GaAs and Ge. 
     
     
         3 . The composition according to  claim 1 , the composition ranges for Ga 1-x In x N y As 1-y-z Sb z  being 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03. 
     
     
         4 . A multijunction solar cell comprising:
 at least one subcell comprising Ga 1-x In x N y As 1-y-z Sb z , with a low antimony (Sb) content and enhanced indium (In) content and enhanced nitrogen (N) content to achieve a bandgap of at least 0.9 eV.   
     
     
         5 . The multijunction solar cell according to  claim 4 , the adjacent substrate being selected from the group GaAs and Ge. 
     
     
         6 . The multijunction solar cell according to  claim 4 , the composition ranges for Ga 1-x In x N y As 1-y-z Sb z  being 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03. 
     
     
         7 . A method for manufacturing a multijunction solar cell comprising:
 forming a first subcell of an alloy of Ga 1-x In x N y As 1-y-z Sb z , with a low antimony (Sb) content and enhanced indium (In) content and enhanced nitrogen (N) content, the composition being selected to achieve at least a 0.9 eV bandgap; and   joining the first subcell with at least one adjacent subcell to form the multijunction solar cell.   
     
     
         8 . The method according to  claim 7 , the composition ranges for Ga 1-x In x N y As 1-y-z Sb z  being 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03. 
     
     
         9 . The method according to  claim 7 , the Ga 1-x In x N y As 1-y-z Sb z  subcell being substantially lattice matched to a substrate selected from the group GaAs and Ge.