Book/Dissertation / PhD Thesis

FZJ-2023-02871

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Hafnium oxide based memristive devices as functional elements of neuromorphic circuits

Cüppers, F. (Corresponding author)FZJ*

2023
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-702-8

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Please use a persistent id in citations: doi:10.34734/FZJ-2023-02871

Abstract: Due to the approaching limit of the computational speed of classical von-Neumann architectures, data transfer-intensive cognitive applications in future information technology demand a paradigm shift. "Beyond-von Neumann" concepts such as biologically inspired neuromorphic circuits with adjustable synaptic weights promise an energy-efficient increase in computing power. In this context, novel memristive devices such as redox-based resistive random access memories (ReRAM) are investigated intensively. They combine nonvolatility, scalability and energy efficiency. Moreover, they also allow the programming of multiple different resistive states, which further increases the memory density in addition to the compact design. Due to their mixed ionic-electronic function, they differ significantly from purely electronic systems. Important criteria for the use of memristive devices in neuromorphic circuits are the operation parameters for the two switching modes abrupt and analog switching, the stochasticity of the switching processes SET and RESET, the variability of the resistance states HRS and LRS as well as the number of programmable states. In addition to the quantification of these parameters, the physical understanding of the processes taking place is crucial in order to make predictive statements about applicability and reliability in circuits. In this context, the exchange with and further development ofphysical models is essential. A typical filamentary ReRAM cell operating in the bipolar valence change mechanism (VCM) is composed of one or more insulating metal oxide layers and two metal electrodes, which differ in terms of work function and chemical reactivity. A preferred choice for the metal oxide layer by the industry is HfO2, since it is already available in semiconductor device fabrication lines. By intentionally introducing an additional sub-stoichiometric titanium oxide layer and using a chemically reactive titanium electrode and an inert platinum electrode, reproducible and stable switching behavior is obtained. In this work, the described switching modes are systematically analyzed on nanoscale Pt/HfO2/TiOx/Ti/Pt devices based on statistical ensembles. The devices are highly comparable to industrially available options. With the aid of compact model simulations, the results are physically interpreted to obtain a comprehensive description of the devices as a foundation for usage in future "Beyond-von Neumann" concepts. The results allow an evaluation of the HfO2-based ReRAM cells with respect to their application in novel neuromorphic circuits.

Note: Dissertation, RWTH Aachen University, 2023

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Contributing Institute(s):

1. JARA Institut Green IT (PGI-10)

Research Program(s):

1. 899 - ohne Topic (POF4-899) (POF4-899)

Appears in the scientific report 2023

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