LARGE-AREA GAINASP AND GAINP SOLAR-CELLS FOR SPACE APPLICATIONS

We report the fabrication and characterization of large area (1 x 1 cm (2)) Ga0.84In0.16As0.68P0.32 (E(g)=1.50eV) and Ga0.51In0.49P (E(g)=1.8 8 eV) solar cells. The cell structures were grown by gas-source MBE on 2 '' (100) GaAs substrates. For the GaInAsP material, both n-on-p and p-on-n structures having wide-gap Ga0.51In0.49P window were studied. The GaInAsP n-on-p cells showed significantly better active area conve rsion efficiencies (17.8% at AMO, 1-sun illumination) than p-on-n stru ctures (13.0%, same conditions) mostly due to lower sheet resistance o f the n-type GaInAsP emitter layers. For GaInP cells the best conversi on efficiency of 11.0% was achieved for windowless shallow homojunctio n n-on-p structure. Since only single layer of SiNx was utilized as an antireflection coating for all the cells, we believe that the applica tion of an optimized two-layer antireflection coatings could increase the efficiencies up to 19% and 14% for GaInAsP and GaInP solar cells, correspondingly. The excellent uniformity in all the cell parameters a cross the 2 '' wafers indicates that larger area solar cells (up to 10 cm(2)) can be fabricated.