Transient Study of Femtosecond Laser-Induced Ge2Sb2Te5 Phase Change Film Morphology

Femtosecond laser-induced crystallization and ablation of Ge2Sb2Te5 (GST) phase change film is investigated by reflectivity pump-probing technology. Below the ablation threshold, the face-centered cubic structure (FCC) state in the central area can be formed, and cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter. The time of surface temperature dropping to the crystallization point needs about 30 ps for 5.86 mJ/cm(2) and 82 ps for 7.04 mJ/cm(2), respectively. At higher laser fluence, crystallization GST island structures appear in the central ablation region due to the extremely short heating time (100 ps). Furthermore, crystallization rate is faster than the ablation rate of the GST film, which is caused by different reflectivity.

Automated summary

Femtosecond laser-induced crystallization and ablation of Ge2Sb2Te5 (GST) phase change film were studied using reflectivity pump-probing technology. Different crystallization structures and rates were observed at different laser fluences. The crystallization rate was found to be faster than the ablation rate of the GST film due to different reflectivity properties.