GaInP/GaAs cascade solar cells grown by molecular beam epitaxy

First results for molecular beam epitaxy (MBE) grown Ga/sub 0.51/In/sub 0.49/P/GaAs cascade solar cells are presented. The structures were prepared by both solid-source (SS) MBE and gas-source (GS) MBE. The tunnel diodes between the subcells were grown by using the standard MBE dopants (silicon and beryllium) but dopant diffusion related degradation of the cell characteristics was not observed. For the best SSMBE structure, a conversion efficiency of 21.1% was measured at AM0 for a 1/spl times/1 cm/sup 2/ cell. For the GSMBE structures, the best AM0 conversion efficiency was 20.8% for a 2/spl times/2 cm/sup 2/ device. In addition, the first MBE results for advanced Al/sub 0.51/In/sub 0.49/P/Ga/sub 0.51/In/sub 0.49/P-based tunnel diodes are presented.