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Nanoscale Topotactic Phase Transformation in SrFeO x Epitaxial Thin Films for High‐Density Resistive Switching Memory
Author(s) -
Tian Junjiang,
Wu Haijun,
Fan Zhen,
Zhang Yang,
Pennycook Stephen J.,
Zheng Dongfeng,
Tan Zhengwei,
Guo Haizhong,
Yu Pu,
Lu Xubing,
Zhou Guofu,
Gao Xingsen,
Liu JunMing
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201903679
Subject(s) - materials science , nanoscopic scale , brownmillerite , phase (matter) , perovskite (structure) , nanotechnology , non volatile memory , optoelectronics , chemical engineering , chemistry , organic chemistry , engineering
Resistive switching (RS) memory has stayed at the forefront of next‐generation nonvolatile memory technologies. Recently, a novel class of transition metal oxides (TMOs), which exhibit reversible topotactic phase transformation between insulating brownmillerite (BM) phase and conducting perovskite (PV) phase, has emerged as promising candidate materials for RS memories. Nevertheless, the microscopic mechanism of RS in these TMOs is still unclear. Furthermore, RS devices with simultaneously high density and superior memory performance are yet to be reported. Here, using SrFeO x as a model system, it is directly observed that PV SrFeO 3 nanofilaments are formed and extend almost through the BM SrFeO 2.5 matrix in the ON state and are ruptured in the OFF state, unambiguously revealing a filamentary RS mechanism. The nanofilaments are ≈10 nm in diameter, enabling to downscale Au/SrFeO x /SrRuO 3 RS devices to the 100 nm range for the first time. These nanodevices exhibit good performance including ON/OFF ratio as high as ≈10 4 , retention time over 10 5 s, and endurance up to 10 7 cycles. This study significantly advances the understanding of the RS mechanism in TMOs exhibiting topotactic phase transformation, and it also demonstrates the potential of these materials for use in high‐density RS memories.