O-doped GeTe/Sb₂Te₃ multilayer chalcogenide for multi-level phase-change device

Abstract In this study, an O-doped GeTe/Sb 2 Te 3 multilayer chalcogenide was investigated for a multi-level phase-change device. O-doped GeTe (OGT) (O concentration of 14.4%) and Sb 2 Te 3 (OST) (O concentration of 3.6%) exhibited different behaviors of lattice constant based on X-ray diffraction analysis. The former and the latter showed a general increase and decrease in lattice constant with annealing temperature, respectively. The latter had face-centered cubic and hexagonal crystal structures, while the former had only one face-centered cubic structure. The multilayer of [OGT (6.25 nm)/OST (6.25 nm)] 16 exhibited a 2-step drop in resistivity. This means that the resistivity can be well controlled by combining two different chalcogenides, which enables a stable intermediate state. Compared with only one resistance drop of single-layer OGT and OST devices, two clear resistance drops were observed in the I-V characteristics of the device using the [OGT (6.25 nm)/OST (6.25 nm)] 16 , implying a high storage density.