Understanding the crystallization mechanism of Ge-Te-Ti phase change material

In this study, we proposed Ge-Te-Ti (GTT) as a novel phase change material for high data retention use. Just with a small Ti fraction, the temperature for 10-yr´s data retention reaches 175°C, and the grain size decreases on order of magnitude. In order to reveal the physical origin of thermal stability variation trend, we performed isothermal sheet resistance measurement combining with Johnson-Mehl-Avrami-Kolmogrov (JMAK) analysis to understand the crystallization processes of GeTe and GTT. Referring to the variation trend of incubation time and effective rate constant, we can reasonably come to the conclusion that compared to pure GeTe, both the nucleation and growth process of GTT are greatly suppressed, thus providing much larger crystallization temperature and activation energy. Then we can know that the small amount of Ti doping (0.2~1.2%) can prolong the incubation time and slow down the growth speed, which can be seen as the kinetic origin for thermal stability enhancement.