SJ and TJ GaAs concentrator solar cells on Si virtual wafers

GaAs solar cells grown on Si wafers have been investigated for many years to find a way to reduce the solar cell cost, by replacing the expensive Ge substrates with a low cost material and less heavy. Both space and terrestrial applications are interested in the development of this type of technology. This paper is presenting the most recent results on this subject. The preparation of so called Si:Ge "virtual wafers" was carried out with a new approach for Ge deposition on Si wafers, originally developed for microelectronic. Both single junction and triple junction GaAs solar cells were manufactured and preliminary tested. Solar cells ranging from a size of 8 cm/sup 2/ down to 1 mm/sup 2/ were manufactured for terrestrial applications in concentrator systems.