Opto-electrical simulation of III-V nanowire based tandem solar cells on Si

Due to their nanostructured surface, nanowire-based solar cells are interesting structures to increase light absorption in thin film solar cells. Among these structures, III-V nanowires grown on silicon substrates to obtain a tandem solar cell are particularly interesting to absorb selectively different part of the solar spectrum and to reduce thermalization effects. The aim of this work is to perform optical and electrical simulations of tandem solar cells based on III-V nanowires on silicon and to compare two different III-V semiconductor compounds (GaAs_0.8P_0.2 and Ga_0.8Al_0.2As) with a band gap of 1.7 eV (optimal on Si) for the nanowire array. Optical simulations are performed with an in-house Rigorous Coupled Wave Analysis (RCWA) software by taking into account the current matching between the two solar cells. Electrical simulations are performed with the TCAD software Sentaurus. Opto-electrical simulations demonstrate that optimal geometries and efficiencies are very similar for the two semiconductors used for the nanowires.