Polycrystalline GaAs solar cells on low-cost Silicon-FilmTM substrates

The authors assess the potential of a low-cost, large-area Silicon-Film^TM sheet as a substrate for thin-film polycrystalline GaAs solar cells. Silicon-Film^TM is a relatively inexpensive material on which large-grain (>2 mm) polycrystalline GaAs films can be formed. The GaAs epitaxial layers are grown by a simple close-spaced vapor transport (CSVT) technique using water vapor as a transport agent. A recrystallized Ge_1-xSi _x buffer layer between the GaAs epilayer and Silicon-Film^TM substrate can facilitate growth of the GaAs. Selective epitaxy on patterned, oxide-masked substrates is effective in reducing thermal stress effects