Development of 1.25 eV InGaAsN for triple junction solar cells

Current GaInP/sub 2//GaAs/Ge triple junction solar cells currently starting production at EMCORE have achieved average lot efficiencies of greater than 26%, with an EOL/BOL of 92% for exposure to 1 MeV electrons at a fluence of 5/spl times/10/sup 14/ e/cm/sup 2/. Development of the next generation high efficiency multijunction solar cell will involve the development of new materials lattice matched to GaAs. One material of interest is 1.05 eV InGaAsN, to be used in a four junction GaInP/sub 2//GaAs/InGaAsN/Ge device. Despite several years of effort, the development of the 1.05 eV InGaAsN material has been difficult. As an alternative, they have been looking at 1.25 eV InGaAsN for use in a GaInP/sub 2//InGaAsN/Ge triple junction cell. The authors present results for their work with the 1.25 eV InGaAsN material.