Time-resolved reflectivity of ion-implanted silicon during laser annealing

The time-resolved reflectivity at 0.63 μm from arsenic-implanted silicon crystals has been measured during annealing by a 1.06-μm laser pulse of 50-ns duration. The reflectivity was observed to change abruptly to the value consistent with liquid silicon and to remain at that value for a period of time which ranged from a few tens of nanoseconds to several hundreds of nanoseconds, depending on the annealing pulse intensity. Concurrently, the transmission of the primary annealing beam dropped abruptly. These observations confirm the formation of a metallic liquid phase at the crystal surface during the annealing process.