On the role of Na and modifications to Cu(In,Ga)Se/sub 2/ absorber materials using thin-MF (M=Na, K, Cs) precursor layers [solar cells]

The growth and characterization of Cu(In,Ga)Se/sub 2/ polycrystalline thin film solar cells under the presence of thin-MF (M=Na, K, Cs) precursor layers is presented. Some electrical, structural and electronic absorber properties due to the presence of such Group Ia impurities are quantified along with their influence in device performance. The authors present a growth model for the role of Na in Cu(In,Ga)Se/sub 2/ that attributes the enhancements in electrical conductivity and photovoltaic device performance to the extinction of a finite number of donor states (i.e., In/sub Cu/) at the bulk and grain-boundary regions.