Ultrathin, high-efficiency solar cells made from GaAs films prepared by the CLEFT Process

Solar cells with conversion efficiencies as high as 17% at AM1 have been fabricated from single-crystal 10-µm-thick GaAs films prepared by the CLEFT process. These cells are the first devices to employ CLEFT films. In making a cell, a GaAs film with an n⁺/p/p⁺shallow-homojunction structure is grown by vapor-phase epitaxy on a specially masked single-crystal GaAs substrate, then transferred to a glass substrate that serves as the cell cover glass. The GaAs substrate can be reused repeatedly for preparing additional CLEFT films.