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May 16-17, 2019 | Prague, Czech Republic
2
nd
International Conference on
22
nd
International Conference on
Nanomaterials and Nanotechnology
Advanced Nanoscience and Nanotechnology
Joint Event
&
Journal of Materials Science and Nanotechnology | Volume 3
Mater Sci Nanotechnol, Volume 3
Electrical characteristics of single nanowire TiO
2
memristive devices in air and
vacuum at room temperature
Sahar Alialy, John J Boland, Claudia Gomes da Rocha
and
Mauro Ferreira
Trinity College Dublin, Ireland
T
he performance of memristive devices are of huge
interest today due to their wide use in nanoelectronics
with applications in non-volatile memory and storage,
and neuromorphic computing. The resistive switching (RS)
properties of these devices have shown a range of different
behaviours regarding the nature and direction of hysteresis
loops. In particular, the presence and origin of the negative
differential resistance (NDR) regions found in these hysteresis
loops has attracted a lot of interest. In this study, we report
the resistive switching properties of a single nanowire of Au-
Ti/TiO
2
/Ti-Au RRAM devices at room temperature in air and
under vacuum. The Clockwise Switching (CWS) and clear NDR
regions of the I-V characteristics of the device in vacuum are
transformed into bipolar Counter-Clockwise Switching (CCWS)
without NDR regions when measurements were made in air.
The current level also increased significantly in air comparing
with vacuum. We explain this behaviour based on the creation
of oxygen vacancies under voltage bias at one interface, and
the drift of these charge carriers toward the cathode. These
vacancies in the vacuum act as shallow donors and dopants
diffuseunderbiastocreatemultipledepletionregionsalongthe
wire resulting in the NDR behaviour. The presence of oxygen in
airresultsinrecombinationoftheoxygenvacancies,quenching
the NDR effect and switching the direction of the hysteresis
loop. The dynamics of the depletion layer is described using
a phenomenological memristor model based on the Hewlett-
Packard (HP) Labs picture inwhich complex charge conduction
phenomena can be captured by fitting ion-drift equations
with the experimental data. This study demonstrates that the
RS and memristive properties of devices are dependent on
the ambient conditions and these results will help facilitate
future applications of these devices in highly dense random-
access memories and brain-like (neuromorphic) devices.
e
:
alialy.sahar@gmail.com