5-junction III-V solar cells for space applications

Monolithic multi-junction III-V solar cells with five active junctions, namely AlGaInP, GaInP, AlGaInAs, GaInAs and Ge have been realized for the first time. An open circuit voltage of 4826 mV was measured. The cells are expected to benefit of a superior radiation hardness as the thickness of each individual subcell is only in the range of 120-1600 nm. The measurement of important parameters like the IV-characteristics or the quantum efficiency of individual subcells is extremely challenging but first measurements were successful and are discussed in this paper.