A 2D numerical study on the photo current density enhancement in silicon solar cells with optimized backside gratings

In this work, we present a detailed numerical study on the optimization of the photo current density in silicon solar cells with rectangular aluminum backside gratings covered with a 100 nm thick SiO₂ layer. The simulation method combines a 2D ray tracing algorithm with rigorous coupled wave analysis for calculating the grating diffraction efficiencies. The optimization was performed for gratings with period lengths ranging from 0.25 μm to 1.5 μm and modulation depths ranging from 25 nm to 400 nm under the assumption of normal light incidence. The flat front side is covered with an 80 nm thin silicon nitride anti-reflection coating. The simulations show that the optimum grating parameters resulting in a maximum photo current density strongly depend on the silicon thickness.