Design of Passivation Layers on Axial Junction GaAs Nanowire Solar Cells

We design a surface passivation scheme for axial junction GaAs nanowire solar cells and simulate its performance by coupled optical and electrical simulations. This design uses a wide bandgap AlGaAs shell layer to generate modulation doping in the active region and protect photogenerated carriers from the surface and top contact. The design has both excellent optical and electrical properties and achieves 21.3% power conversion efficiency when using realistic material parameters, which is 2.7 times higher than an optimized bare nanowire. Furthermore, the design is largely insensitive to surface quality and junction position, assuming moderate bulk material quality.