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High temperature solid phase epitaxial crystallization of amorphous silicon layers prepared by electron beam evaporation (EBE) is investigated. By using a cw diode laser for heating the films rapidly (in milliseconds to seconds) this method is suitable on glass substrates with low temperature resistance. Therefore, the method is an economically advantageous technique of producing absorber layers for thin film solar cells. The experiments were carried out on monocrystalline wafers of different orientations and on polycrystalline seed layers on glass. The crystallization process was monitored in situ by time resolved reflectivity measurements. Up to 500 nm thick films were successfully crystallized epitaxially. Depending on the crystal orientation of the substrate 2 s to 3 s were needed to complete epitaxy. The evolution of temperature during crystallization was simulated numerically.