Vacancy
Associates-Rich Ultrathin Nanosheets for High
Performance and Flexible Nonvolatile Memory Device
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Abstract
On
the road of innovation in modern information technology, resistive
switching random access memory (RRAM) has been considered to be the
best potential candidate to replace the conventional Si-based technologies.
In fact, the key prerequisite of high storage density and low power
consumption as well as flexibility for the tangible next generation
of nonvolatile memories has stimulated extensive research into RRAM.
Herein, we highlight an inorganic graphene analogue, ultrathin WO<sub>3</sub>·H<sub>2</sub>O nanosheets with only 2–3 nm thickness,
as a promising material to construct a high performance and flexible
RRAM device. The abundant vacancy associates in the ultrathin nanosheets,
revealed by the positron annihilation spectra, act not only carrier
reservoir to provide carriers but also capture center to trap the
actived Cu<sup>2+</sup> for the formation of conductive filaments,
which synergistically realize the resistive switching memory with
low operating voltage (+1.0 V/–1.14 V) and large resistance
ON/OFF ratio (>10<sup>5</sup>). This ultrathin-nanosheets-based
RRAM
device also shows long retention time (>10<sup>5</sup> s), good
endurance
(>5000 cycles), and excellent flexibility. The finding of the existence
of distinct defects in ultrathin nanosheets undoubtedly leads to an
atomic level deep understanding of the underlying nature of the resistive
switching behavior, which may serve as a guide to improve the performances
and promote the rapid development of RRAM