Tunable crystallization mechanism of Sb₄Te films by VO₂ nano-grid framework for breaking through the trade-off between thermal stability and crystallization speed

The thermal stability and optical bandgap of the amorphous Sb₄Te film can be improved significantly by combining with VO₂, which leads to a high crystallization temperature (around 220 °C), good data retention (ten-year data retention above 130 °C), and high amorphous resistance. The crystallization mechanism of Sb₄Te changes from growth-dominated mode into nucleation-dominate one, which is confirmed by in situ microstructure observation experimentally and crystallization kinetics index theoretically, due to the long-range orders of Sb–Te and Sb–Sb bonds disorganized by the introduction of VO₂ nano-grid framework. The Sb₄Te crystallites can be refined and confined in the VO₂ nano-grid framework. VO₂–Sb₄Te films with less than 15 at.% of VO₂ maintain the high crystallization speed. The nano-grid framework of VO₂ enables an efficient way to invade the long-order bonds of Sb₄Te, which improves the rigid trade-off between thermal stability and crystallization speed. It provides a novel clue for optimizing other phase-change materials. (paper)