Multi-junction cells with monolithic bypass diodes

Bypass diodes are attached electrically parallel (but with opposite polarity) to solar cells such that when the cells are reverse biased, the bypass diodes are forward biased, passing current and preventing the cells from going into reverse breakdown. For III-V single and multi-junction space cells, discrete silicon bypass diodes have typically been used. In this paper, we present a monolithic bypass diode, grown on top of the III-V solar cell. The bypass diode is of opposite polarity to the cell, but electrically parallel to the cell. The advantage of the monolithic diode over the discrete diode is the reduction in interconnects and handling required during the interconnecting of cells into strings. We present performance, reliability, and space qualification results for the monolithic bypass diode. Of particular importance are the diode reverse bias leakage current and the forward bias turn-on voltage. Large area (/spl sim/30 cm/sup 2/) cell/monolithic diodes with efficiencies of 28% have been made.