Observation of ultrafast amorphization dynamics in GeCu₂Te₃ thin films using echelon-based single-shot transient absorbance spectroscopy

The compound GeCu₂Te₃ (GCT) has attracted considerable attention because of its several advantages for next-generation nonvolatile memories, including its higher thermal stability and lower volume change, with large optical contrast between the crystalline and amorphous phases. In this study, we demonstrate the ultrafast amorphization dynamics that occur in GCT by utilizing echelon-based single-shot transient absorbance spectroscopy and coherent phonon spectroscopy. We find that the timescale of the absorbance change accompanying amorphization is ∼2 ps, which is close to the dephasing time of the A₁ optical phonons. Based on the observed results and the robust structural network of crystalline GCT, we discuss the amorphization dynamics in GCT by comparing it with that in the typical phase-change material Ge₂Sb₂Te₅.