Different crystallization processes of as-deposited amorphous Ge2Sb2Te5 films on nano- and picosecond single laser pulse irradiation

The crystallization dynamics of as-deposited amorphous Ge2Sb2Te5 films induced by nano- and picosecond single laser pulse irradiation is studied using in situ reflectivity measurements. Compared with nanosecond laser pulse, the typical recalescence phenomenon did not appear during the picosecond laser pulse-induced crystallization processes when the pulse fluence gradually increased from crystallization to ablation threshold. The absence of melting and recalescence phenomenon significantly decreased the crystallization time from hundreds to a few tens of nanoseconds. The role of pulse duration time scale on the crystallization process is qualitatively analyzed.