A method for producing a mono-crystalline sheet includes providing at least two aperture elements forming a gap in between; providing a molten alloy including silicon in the gap; providing a gaseous precursor medium comprising silicon in the vicinity of the molten alloy; providing a silicon nucleation crystal in the vicinity of the molten alloy; and bringing in contact said silicon nucleation crystal and the molten alloy. A device for producing a mono-crystalline sheet includes at least two aperture elements at a predetermined distance from each other, thereby forming a gap, and being adapted to be heated for holding a molten alloy including silicon by surface tension in the gap between the aperture elements; a precursor gas supply supplies a gaseous precursor medium comprising silicon in the vicinity of the molten alloy; and a positioning device for holding and moving a nucleation crystal in the vicinity of the molten alloy.