Abstract
Phase transition (amorphization and crystallization) of Si by ultrashort pulse laser irradiation is reported in this paper. We investigated the dependences of ablation rate and fluence for amorphization on laser pulse width [1], Laser pulse width was changed in the range of 100fs-200ps. The amorphization resulted in increasing laser absorption and hence decreasing the ablation threshold. From the TEM observation (shown in Fig.l), creation of thin amorphous layer, which showed almost uniform thickness of about 50nm, was confirmed. The thickness of the amorphized layer did not depend on the number of irradiated laser pulses and fluence. The range of the laser fluences that induced the amorphization became broader with decreasing laser pulse width, and shorter laser pulse could induce amorphization with lower fluence. It was required for inducing the amorphization that the pulse width was shorter than 8ps.
© 2007 IEEE
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