Lithography-Free Mesa Isolation of III-V Solar Cells Through Laser Ablation

Eliminating photolithography from solar cell processing is a significant opportunity for cost reduction for III-V solar cells. In this work, we explore femtosecond laser ablation as an alternative to contact photolithography and wet chemical etching for mesa isolation. We demonstrate both GaAs and GaInP solar cells mesa-isolated by femtosecond laser ablation with minimal to no loss in solar cell performance. We show the best results with a 400 fs UV pulsed laser and a short clean-up etch that also serves as a contact layer removal etch.