Reflective Barrier Optimization in Ultrathin Single-Junction GaAs Solar Cell

This paper proposes a theoretical analysis of electronic transport in ultrathin (220 nm) single-junction GaAs solar cell. Using an in-house electronic quantum transport model, we shed light on two detrimental phenomena, namely the “backdiffusion” and the “contact-to-contact diffusion.” While the back-diffusion degrades both the short-circuit current and the fill factor, the contact-to-contact diffusion reduces the open-circuit voltage. The so-called window and back-surface-field barriers used to reflect minority carriers away from contacts reduce these two detrimental phenomena. In a second part, we then show a synthesis of performance optimization of window/GaAs/backsurface-field heterojunctions varying thicknesses, materials, and material composition profiles. Our results conclude that the Al_0.4Ga_0.6As(10 nm)/GaAs/In_0.49Ga_0.51P(10 nm) structure provides the best output power.