Change in Crystallization Mechanism of Sb Film by Doping VO₂ for Ultraretention and High-Speed Phase-Change Memory

Abstract

Pure Sb thin film has attracted great interest for phase-change memory owing to its appealing properties such as simple composition, fast crystallization, and sufficient electrical contrast between amorphous and crystalline states. However, its proneness to crystallization dominated by an explosive mechanism makes it challenging to achieve a stable amorphous state. Here we demonstrate a high thermal stability of amorphous Sb which is realized by combining with a VO2 grid-frame structure to vary its crystallization mechanism. It is shown that the crystallization temperature and 10-year data retention increased with the increasing VO2 concentration. A higher crystalline resistance for (VO2)xSb100–x thin film was obtained due to the existence of the abundant Sb-VO2 grain boundaries, which is beneficial to reduce the power consumption. The optical band gaps of both as-deposited and crystalline films increase with increasing VO2 content. After the addition of VO2, the crystallization mechanism changes from explosive crystallization to a nucleation-dominated crystallization mechanism, which results in the improvement of thermal stability. These results pave the way for building a high-stability and high-speed phase-change memory based on simple composition.