Increase of switching range of resistive memristor for realization of a greater number of synaptic states in a neuroprocessor

About the authors:

Andrey N. Bobylev, Head of the Laboratory of Electronic and Probe Microscopy. REC “Nanotechnology”, University of Tyumen; eLibrary AuthorID, ScopusID, andreaubobylev@gmail.com; ORCID: 0000-0001-5488-8736

Sergey Yu. Udovichenko, Dr. Sci. (Phys.-Math.), Professor, Department of Applied and Tech­nical Physics, School of Natural Sciences, University of Tyumen, Tyumen, Russia; Scientific Director of the Memristive Materials Laboratory, Center for Nature-Inspired Engineering, University of Tyumen, Tyumen, Russia; udotgu@mail.ru, https://orcid.org/0000-0003-3583-7081

Alexander N. Busygin, Cand. Sci. (Phys.-Math.), Associate Professor, Department of Applied and Technical Physics, School of Natural Sciences, University of Tyumen, Tyumen, Russia; Senior Researcher, Memristive Materials Laboratory, Center for Nature-Inspired Engineering, University of Tyumen, Tyumen, Russia; a.n.busygin@utmn.ru, https://orcid.org/0000-0002-3439-8067

Abdulla H. Ebrahim, Cand. Sci. (Phys.-Math.), Junior Researcher, Memristive Materials Laboratory, Center for Nature-Inspired Engineering, University of Tyumen, Tyumen, Russia; abdulla.ybragim@mail.ru, https://orcid.org/0000-0002-1709-9882

Abstract:

In a promising nanoelectronic device — a memristor based on metal oxides, there are many intermediate states with different conductivity between the high- and low-conducting states. These states can be used in the processes of associative learning of a neural network based on memristor synapses and simultaneous input pulses processing, which consists of pulses weighing and summation in a neuroprocessor.

Using the method of simultaneous magnetron sputtering of two cathodes in a reactive oxygen environment, the authors obtained thin films of mixed oxides with a different mole fraction of titanium and aluminum. In addition, this article describes the method of obtaining a mixed oxide with a specified metals fraction by controlling the sputtering rates of cathodes using acoustic piezoelectric sensors.

The results show that the addition of Al into titanium oxide improves the electrophysical characteristics of the memristor. The authors proved the existence of an optimal mole fraction of Al impurity, at which the maximum ratio of the resistances of the memristor in the high-resistance and low-resistance states. The results indicate that the method of reactive magnetron deposition of mixed metal oxide by simultaneous sputtering of two cathodes provides a more uniform distribution of elements across the thickness of the active layer compared with the atomic layer deposition method. That increase of uniformity is necessary to improve the stability of the memristor.

It can be expected that in the memristors on the mixed oxides Ti_xSc_1−xO_y, Hf_xSc_1−xO_y, Hf_xY_1−xO_y, Hf_xLu_1−xO_y, Zr_xSc_1−xO_y, Zr_xY_1−xO_y, Zr_xLu_1−xO_y, an optimal impurity fraction corresponding to the high and low resistances ratio maximum will be observed. Moreover, memristors on pure films of pure hafnium and zirconium oxides have a much larger range of resistive switching than titanium oxide.

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