Method for producing multi-layer, thin-film, flexible silicon alloy

Abstract

Method and apparatus for producing multi-layer, thin-film flexible photovoltaic cells with front and rear junction regions electrically in series and formed of ceramic glass semi-conductor alloys of silicon laminated with an intervening semi-conducting layer less than 60 Angstroms thick or an insulating layer less than 20 Angstroms thick. The respective spectral sensitivities of front and rear junction regions are in different frequency ranges. The method and apparatus include providing two ribbons of the silicon alloy in a molten state, passing the molten ribbons between respective first pairs of opposed rollers in first rolling stations, cooling the first pairs of rollers for rapidly cooling the molten ribbons to semi-solidus condition, then passing them between other pairs of opposed rollers in other rolling stations at a ribbon temperature in the range from 740.degree. C. to 1130.degree. C. for promoting crystal growth in the ribbons while being rolled. The two ribbons are laminated together and then suddenly quenched for stopping further crystal growth. The ribbons are shown initially formed by extruding. They are kept 20.degree. C. to 60.degree. C. below the semi-liqudus condition of the silicon alloy. The quenching occurs in a liquid etchant bath. Doping of the ribbons and ion implantation are carried out before laminating them together.