Crystal-Like Glassy Structure in Sc-Doped BiSbTe Ensuring Excellent Speed and Power Efficiency in Phase Change Memory.

Phase change memory (PCM) is regarded as a promising technology for storage-class memory and neuromorphic computing, owing to the excellent performances in operation speed, data retention, endurance, and controllable crystallization dynamics, whereas the high power consumption of PCM remains to be a short-board characteristic that limits its extensive applications. Here, Sc-doped Bi0.5Sb1.5Te3 has been proposed for high-speed and low-power PCM applications. An operation speed of 6 ns and a threshold current of 0.7 mA have been achieved in 190 nm Sc0.23Bi0.5Sb1.5Te3 PCM, which consumes lower power than GeSbTe and ScSbTe PCM. A good endurance of 5 × 105 has been achieved, which is attributed to the small volume change of 4% during phase change and a good homogeneity phase in the crystalline state. The structure of amorphous Sc0.23Bi0.5Sb1.5Te3 has been characterized by experimental and theoretical methods, showing the existence of a large amount of crystal-like structural factions, which can efficiently minimize the atomic movements required for crystallization and subsequently improve the operation speed and power efficiency. The low diffusivity of Sc and Bi at room temperature and the rapidly increased diffusivity of Bi at elevated temperatures are fundamental for the high data retention of 94 °C and the fast crystallization in Sc0.23Bi0.5Sb1.5Te3. The combination of high atomic mobility and minimized atomic movements during crystallization ensures the high speed and low power consumption of Sc0.23Bi0.5Sb1.5Te3 PCM, which can promote its application to energy-efficient systems, that is, AI chips and wearable electronics.