Ge/Sb_2Te_3 nanocomposite multilayer films for high data retention phase-change random access memory application

摘要

The amorphous-to-crystalline transition of Ge/Sb_2Te_3 nanocomposite multilayer films with various thickness ratios of Ge to Sb_2Te_3 were investigated by utilizing in situ temperature-dependent film resistance measurements. The crystallization temperature and activation energy for the crystallization of the multilayer films increased with the increase in thickness ratio of Ge to Sb_2Te_3. The difference in sheet resistance between amorphous and crystalline states could reach as high as 10~4 Ω/□. The crystallization temperature and activation energy for the crystallization of Ge/Sb_2Te_3 nanocomposite multilayer films was proved to be larger than that of conventional Ge_2Sb_2Te_5 film, which ensures a better data retention for phase-change random access memory (PCRAM) use. A data retention temperature for 10 years of the amorphous state [Ge (2nm)/Sb_2Te_3 (3nm)]_(40) film was estimated to be 165℃ Transmission electron microscopy (TEM) images revealed that Ge/Sb_2Te_3 nanocomposite multilayer films had layered structures with clear interfaces.