NOVELTY - Recrystallizing a solid layer of material, comprises: selecting a substrate (305); depositing a first semiconductor layer of first conductivity type (310); scanning the layer with a beam for heating so that a zone N mm wide across entire layer is heated to predetermined temperature; advancing the layer underneath the beam for heating at a rate of M mm/second so that layer material entering the zone is at predetermined temperature in less than one second and the layer material exiting the zone is more than 50 degrees C below predetermined temperature in less than one second after exiting the zone.    USE - The method is useful for recrystallizing a solid layer of material, which is useful in a solar cell (claimed).    ADVANTAGE - The method enables rapid recrystallization by a smaller spot size achievable by a laser beam compared to other techniques, thus creating a higher power density and more efficient transfer of energy during a zone melt recrystallization process.    DETAILED DESCRIPTION - Recrystallizing a solid layer of material, comprises: selecting a substrate (305); depositing a first semiconductor layer of first conductivity type (310); scanning the layer with a beam for heating so that a zone N mm wide across the entire layer is heated to a predetermined temperature; advancing the layer underneath the beam for heating at a rate of M mm/second so that layer material entering the zone is at the predetermined temperature in less than one second and the layer material exiting the zone is more than 50 degrees C below the predetermined temperature in less than one second after exiting the zone, where the layer material leaving the zone solidifies into a predefined morphology. An INDEPENDENT CLAIM is also included for a solar cell comprising: the substrate; and the first semiconductor layer comprising polycrystalline silicon of first conductivity type, where the first semiconductor layer has been recrystallized by the method, so that the silicon grain size in the minimum dimension has a distribution of 0.1-100 mu , where less than or equal to 10% of the grains have a size less than 1 mu and less than or equal to 10% of the grains have a size greater than 10 mu .    DESCRIPTION OF DRAWING(S) - The figure illustrates the layers of the solar cell structure.    Substrate (305)    Barrier layer (307)    First semiconductor layer of first conductivity type (310)    Second semiconductor layer of second conductivity type (315)    Top layer (325)