No abstract

Cache-type phase-change random-access memory is a remaining challenge on the path to universal memory. The recently designed Sc0.2Sb2Te3 (SST) alloy is one of the most promising phase-change materials (PCMs) to overcome this challenge, as it allows subnanosecond crystallization speed to reach the crystalline (“1”) state at elevated temperatures (e.g., 600 K) but years of reliable retention of the amorphous (“0”) state for data storage at room temperature. This contrast in kinetics behavior, upon a relatively small temperature excursion, is more dramatic than that in other PCMs. From the temperature dependence of the crystallization kinetics uncovered via ultrafast differential scanning calorimetry, here, we report an apparent fragile-to-strong crossover in the SST supercooled liquid. We illustrate that two factors are at work simultaneously. First, Sc-stabilized precursors serve as heterogeneous sites to catalyze nucleation, reducing the stochasticity and thereby accelerating the nucleation rate. Second, the SST exhibits an enlarged kinetic contrast between elevated and ambient temperatures. Together they constitute a recipe for the design of PCMs that meets the needs of cache-type nonvolatile memory.

Phase‐change random‐access memory (PCRAM) devices suffer from pronounced resistance drift originating from considerable structural relaxation of phase‐change materials (PCMs), which hinders current developments of high‐capacity memory and high‐parallelism computing that both need reliable multibit programming. This work realizes that compositional simplification and geometrical miniaturization of traditional GeSbTe‐like PCMs are feasible routes to suppress relaxation. While to date, the aging mechanisms of the simplest PCM, Sb, at nanoscale, have not yet been unveiled. Here, this work demonstrates that in an optimal thickness of only 4 nm, the thin Sb film can enable a precise multilevel programming with ultralow resistance drift coefficients, in a regime of ≈10−4–10−3. This advancement is mainly owed to the slightly changed Peierls distortion in Sb and the less‐distorted octahedral‐like atomic configurations across the Sb/SiO2 interfaces. This work highlights a new indispensable approach, interfacial regulation of nanoscale PCMs, for pursuing ultimately reliable resistance control in aggressively‐miniaturized PCRAM devices, to boost the storage and computing efficiencies substantially.