Wet-Chemically Textured Ultra-Thin GaAs Solar Cells with Dielectric/Metal Rear Mirrors
Maarten van Eerden1, Gerard Bauhuis1, Peter Mulder1, Natasha Gruginskie1, Marco Passoni2, Lucio Andreani2, Elias Vlieg1, John Schermer1
1Radboud University, Institute for Molecules and Materials, Department of Applied Materials Science, Nijmegen, Netherlands
/2University of Pavia, Department of Physics, Pavia, Italy

Dielectric/metal mirrors are frequently employed at the rear side of thin-film GaAs solar cells to obtain a highly reflective rear mirror. In this contribution, we show that using simple wet chemistry, this approach can be extended to incorporate light trapping in ultra-thin GaAs solar cells. The rear-side contact layer of ultra-thin GaAs solar cells was textured using a simple, one-step wet chemical approach. A ZnS/Ag double layer was conformally deposited over the textured contact layer to function as a diffusive rear mirror. Local Ohmic contact points provided electrical contact directly to the Ag. The textured solar cells were compared with planar reference cells fabricated on the same wafer and a clear enhancement of long-wavelength quantum efficiency and short-circuit current was observed in the textured cells. Both architectures showed FF > 80% and VOC > 1 V. Additionally, the rear-side texture increases the external luminescent efficiency by enhancing outcoupling of luminescence.