Anomalous crystallization kinetics of ultrafast ScSbTe phase-change memory materials induced by nitrogen doping

Phase-change random access memory has been served as a bridge across the memory wall within the conventional von Neumann computing architecture, owing to its excellent non-volatility and rapid switching. Nitrogen doping in Ge ₂Sb ₂Te ₅ -like phase-change materials (PCMs) was a routine method for enhancing non-volatility of amorphous phases, although sacrificing crystallization speed markedly. Here we introduced N element into Sc _0.3Sb ₂Te ₃ PCM that possesses sub-nanosecond crystallization speed, trying to cope with stability/reliability issues raised by backend thermal-budget processing. However, we observed an abnormal deterioration in thermal stability of N-doped amorphous Sc _0.3Sb ₂Te ₃ films. As compared to the undoped counterparts, they exhibit a weakened fragile-to-strong crossover in viscosity that gives rise to a higher atomic mobility at elevated temperatures while a less rigid vitreous network at low temperatures. Therefore, N doping leads to an accelerated crystal growth rate and a higher steady-state nucleation rate in heterogeneous manner, causing a faster crystallization, whereas the kinetic suffocation contributed by original Sc element as approaching room temperature must have been partially counteracted by N dopant. This acceleration in crystallization kinetics delivers N-doped Sc _0.3Sb ₂Te ₃ as a promising candidate in working memory.