Nanoscale Chemical Heterogeneity Ensures Unprecedently Low Resistance Drift in Cache-Type Phase-Change Memory Materials.

Huang, Jiaen; Chen, Bin; Sha, Gang; Gong, Huang; Song, Tao; Ding, Keyuan; Rao, Feng · Nano Lett · 2023

basic_science · Level V

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Abstract

Phase-change random access memory is a promising technique to realize universal memory and neuromorphic computing, where the demand for robust multibit programming drives exploration for high-accuracy resistance control in memory cells. Here in Sc<sub><i>x</i></sub>Sb<sub>2</sub>Te<sub>3</sub> phase-change material films, we demonstrate thickness-independent conductance evolution, presenting an unprecedently low resistance-drift coefficient in the range of ∼10<sup>-4</sup>-10<sup>-3</sup>, ∼3-2 orders of magnitude lower compared to conventional Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>. By atom probe tomography and <i>ab initio</i> simulations, we unveiled that nanoscale chemical inhomogeneity and constrained Peierls distortion together suppress structural relaxation, rendering an almost invariant electronic band structure and thereby the ultralow resistance drift of Sc<sub><i>x</i></sub>Sb<sub>2</sub>Te<sub>3</sub> films upon aging. Associated with subnanosecond crystallization speed, Sc<sub><i>x</i></sub>Sb<sub>2</sub>Te<sub>3</sub> serves as the most appropriate candidate for developing high-accuracy cache-type computing chips.