Direct cover glass bonding to GaAs and GaAs/Ge solar cells

Electrostatic bonding is being developed as a technique for attaching cover glasses directly to GaAs and GaAs/Ge solar cells. This process eliminates the elastometric adhesive used in conventional cell assemblies, thereby increasing the thermal stability and radiation tolerance of the assemblies. Cover glasses have been electrostatically bonded to GaAs solar cells with minimal (2%) degradation in conversion efficiency. Bonded cells have survived thermal cycling between -180°C and +150°C without degradation. Glass has also been bonded to AR-coated GaAs/Ge wafers. The wafers were then selectively etched to remove the Ge substrate, leaving only the epitaxial GaAs film attached to the glass. This approach may lead to very lightweight high-efficiency thin-film solar cells