Manipulating the Resistive Switching in Epitaxial SrCoO2.5 Thin-Film-Based Memristors by Strain Engineering

作者：Xiang, Xuepeng; Rao, Jingjing; Lim, Chaesung; Huang, Qicheng; Zhao, Shijun; Fan, Zhen^*; Han, Jeong Woo^*; Chen, Yan^*

来源：ACS Applied Electronic Materials, 2022, 4(6): 2729-2738.

DOI：10.1021/acsaelm.2c00244

• SrCoO2.5 thin films
• memristor
• strain
• brownmillerite
• oxygen vacancy

Diverse synaptic and neuronal functionalities often require different switching dynamics for memristors. Here, we demonstrate an effective approach to modulating the switching dynamics in epitaxial thin-film-based memristors by using strain engineering. We apply 0 and -2.74% compressive strains to the brownmillerite SrCoO2.5 (BM-SCO) thin films by epitaxially growing them on (001)-oriented SrTiO3 (STO) and LaAlO3 (LAO) substrates, with Au and La0.7Sr0.3MnO3 (LSM) acting as top and bottom electrodes, respectively. When applying multiple DC voltage sweeps, the Au/BM-SCO/LSM/LAO memristor with compressive strain displays small yet narrowly distributed ON/OFF ratios (averaged at similar to 3.5 with a cycle-to-cycle fluctuation of similar to 17%), while the Au/BM-SCO/LSM/STO memristor with zero strain exhibits larger ON/OFF ratios distributed in a wider range (averaged at similar to 15.5 with a cycle-to-cycle fluctuation of similar to 33%). In the retention tests, the Au/BM-SCO/LSM/LAO memristor exhibits relatively stable high and low resistance states (HRSs and LRSs, respectively). By contrast, for the Au/BM-SCO/LSM/STO memristor, while the HRS remains stable, the LRS relaxes first and eventually converts to a stable intermediate state. Such significant differences in ON/OFF ratio and retention between the two memristors may be associated with the epitaxial strain-mediated oxygen vacancy generation and migration, which effectively modulated the filament growth and rupture dynamics. Therefore, strain engineering represents a rational route for modulating memristor performance for various neuromorphic applications.

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