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The performance of the high-bandgap Cu(Ga,In)Se/sub 2/-based solar cells is still limited by moderate fill factors and short-circuit currents due to incomplete carrier collection. A high recombination velocity at grain surfaces may be responsible for this behavior. In order to improve the performance, etching and passivating treatments with Br/sup 2/-MeOH and KCN have been performed on Ga-rich absorbers, significantly increasing the fill factor and short-circuit current density. Fill factors of up to 56% were achieved for CuGaSe/sub 2//(Zn,Cd)S. The influence of the treatments on the absorber films was analyzed by various means. EDS analysis, scanning electron micrographs, and electrical measurements of conductivity and carrier density prove the removal of Cu/sub 2-x/Se by KCN dip from Cu-rich films. In stoichiometric or Cu-poor films, no change can be seen by these methods. > |
