Abstract
Understanding state-dependent crystallisation kinetics is important for the modelling and design of phase change material (PCM)-based devices, such as multi-level switches. We show how the level of amorphousness (disorder) of antimony-telluride (Sb2Te3) can be controlled using pulsed laser heating, and that the recrystallisation temperature strongly depends on the local atomic configurations in the amorphous structure. Indeed, when Sb2Te3 is amorphized with higher laser powers, its subsequent recrystallisation temperature increases by up to 23 degrees C yet, and counterintuitively the recrystallisation activation energy decreases. This leads to shorter minimum recrystallisation times. This effect is important because it provides a means to switch PCM devices at higher rates through a catalyst-like effect. The optical properties of Sb2Te3 can be gradually tuned by the level of crystallographic disorder. The amorphousness of PCMs provides a further degree-of-freedom to achieve multi-level programmability and tune the switching energy of devices.