Concentration effects of tunnel diode for optimizations of multi-junction solar cells

Tunnel diodes, also known as Esaki diodes, play an important role in III-V multi junction solar cells. In this work, we theoretically investigated the electrical characteristics of a GaAs tunnel diode and its performance against the illumination conditions such as light intensity, spatial profile, etc. We then developed a methodology to optimize a triple junction InGap/GaAs/Ge solar cell with a GaAs tunnel junction. The conversion efficiency drops with the increase of the concentration ratio is also discussed.