Cheap GaAs solar cells grown on acoustically spalled substrates with 27% efficiency

https://techxplore.com/news/2023-07-solar-cells-cheaper.html

"allow cell removal revealing new, contaminant-free surface from within substrate does not require polishing... spalling standard GaAs layers large facets on substrate that consume extra material and may require planarization (via polishing or other methods) before the substrate can be reused... acoustic spalling takes seconds, within substrate parallel to surface control fracture, suppress facet formation and improve substrate flatness, surface less corrugated, minimal or no surface repreparation"