Progress on Substrate Reuse Using Sonic Lift-Off for GaAs-Based Photovoltaics

Andrew B. Sindermann1, Stephen J. Polly1, Pablo Guimera Coll2, Elijah J. Sacchitella1, Brandon M. Bogner1, Mariana I. Bertoni3, Seth M. Hubbard1 1Rochester Institute of Technology, Rochester, NY, United States /2Crystal Sonic Inc., Phoenix, AZ, United States /3Arizona State University, Tempe, AZ, United States

Sonic lift-off is able to reduce average surface facet amplitude without degrading bulk material quality and is thus a promising technology for enabling repeated substrate reuse with GaAs-based photovoltaics.  1-sun AM1.5G illuminated current density-voltage data and spectral response data from four devices at different stages of the spalling process have been presented.  Devices grown on a commercial substrate and then acoustically-spalled as well as devices grown on a previously acoustically-spalled substrate with minimal surface treatment did not show degradation in device performance compared to the control grown on a commercial substrate, which was 17% efficient without anti-reflection coatings.  Devices grown on a previously acoustically-spalled substrate and then spalled exhibited degradation in both short-circuit current density and open circuit voltage for a final 8% efficiency, indicating further process improvements are necessary to realize efficient substrate reuse.