Narrow Bandgap Dilute Nitride Materials for 6-junction Space Solar Cells

Abstract

Narrow bandgap p-i-n dilute nitride GaInNAsSb junctions, for use as bottom cell in 6-junction solar cells, are reported. In particular, we demonstrate a high optical quality for GaInNAsSb junction with a bandgap ~0.78 eV, corresponding to a N content of 6.2%. Under AM0 illumination, such cell exhibits a photocurrent of 36.6 mA/cm2. By extracting the parameters of the experimental cell, we estimate the the AM0 efficiency of a 6-junction multijunction solar cell employing the GaInNAsSb junction, to attain a value of 33%. Further improvements are discussed towards achieving the full potential of the 6-junction design.