Crystallization kinetics of nanoconfined GeTe slabs in GeTe/TiTe2-like superlattices for phase change memories

Superlattices made of alternating blocks of the phase change compound Sb2Te3 and of TiTe2 confining layers have been recently proposed for applications in neuromorphic devices. The Sb2Te3 /TiTe2 heterostructure allows for a better control of multiple intermediate resistance states and for a lower drift with time of the electrical resistance of the amorphous phase. However, Sb2Te3 suffers from a low data retention due to a low crystallization temperature T x . Substituting Sb2Te3 with a phase change compound with a higher T x , such as GeTe, seems an interesting option in this respect. Nanoconfinement might, however, alters the crystallization kinetics with respect to the bulk. In this work, we investigated the crystallization process of GeTe nanoconfined in geometries mimicking GeTe/TiTe2 superlattices by means of molecular dynamics simulations with a machine learning potential. The simulations reveal that nanoconfinement induces a mild reduction in the crystal growth velocities which would not hinder the application of GeTe/TiTe2 heterostructures in neuromorphic devices with superior data retention.