Photoinduced ultrafast and thermally induced amorphization dynamics in tantalum-doped Sb₂Te phase change materials

Phase change material (PCM) based information memory mainly relies on the rapid transition from amorphous and crystalline states of these systems. While extensive research has been focused on the crystallization process of PCM, physical mechanisms on the amorphization process have been limited and insufficiently explored to date. Here, we systematically investigate the amorphization dynamics and local order of tantalum (Ta) -doped Sb₂Te material under thermally induced melting-quenching and photoexcitation processes, using ab initio molecular dynamics and real-time time-dependent density-functional theory methods, respectively. During the melt-quenching process, the doping of Ta atoms enhances local order by promoting the formation of highcoordination and triangular configurations, thereby improving the thermal stability of the amorphous structure. The core mechanism of the pulsed laser-induced amorphization originates from the dynamic modulation of interatomic bonding characteristics by photoexcited carriers, which can reduce the amorphization barrier and drive structural instability. Compared with the former, the latter induces the increase of tetrahedral structure and a higher number of rings in the amorphous process, while the local Peierls distortion attenuates, reducing the risk of resistance drift. This work provides insights on the amorphization dynamics of Ta-doped Sb₂Te and related PCM induced by both thermal and photoexcitation.