HfO2/GaOx Bilayer Resistive Switching Devices for Neural Activity Processing
Onur Toprak a b, Florian Maudet a, Tom Stumpp d, Peter Jones d, Roland Thewes b, Veeresh Deshpande a, Catherine Dubourdieu a c
a Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, Berlin, Germany
b Technical University of Berlin (TU), Straße des 17. Juni, Berlin, Germany
c Freie Universität Berlin, Arnimallee 14, Berlin, Germany
d NMI Naturwissenschaftliches und medizinisches Institut, 72770 Reutlingen, Germany
Proceedings of Neuronics Conference (Neuronics)
València, Spain, 2024 February 21st - 23rd
Organizers: Sabina Spiga and Juan Bisquert
Oral, Onur Toprak, presentation 020
DOI: https://doi.org/10.29363/nanoge.neuronics.2024.020
Publication date: 18th December 2023

Resistive random-access memory (ReRAM) devices have significant potential for low power in-memory and neuromorphic computing. However, there are major challenges that need to be addressed to further progress in this field, particularly in terms of integration into complementary metal-oxide-semiconductor (CMOS) technology [1]. Moreover, the majority of the reported ReRAM devices exhibit low resistance causing sneak current and high-power consumption in circuit applications [2]. Therefore, they require a rectifier for the control of the low resistance state (LRS). In this work, we introduce a new CMOS-compatible self-rectifying bilayer W/GaOx/HfO2/Ti memristive device, where thin amorphous GaOx (5 nm) and HfO2 (4 nm) layers are deposited by atomic layer deposition at low temperature (250 °C). The I-V characteristics of the devices exhibit a hysteretic behavior with access to low resistance and high resistance states with an operating voltage of 3.3 V. Both the HRS and LRS values scale with the electrode area, suggesting a bulk/interfacial-governed switching mechanism. The amorphous GaOx layer provides rectification (no need for a compliance current) due to its semiconducting nature that can be tuned with the deposition parameters [3]. A potentiation depression behavior is evidenced under an identical pulse scheme programming with a low operation voltage (Vwrite = 3.2 V). In this voltage range, good compatibility with CMOS devices is achieved. Low writing (~ 260 nA/µm²) and reading currents (~100- 600 pA/µm²) can enable low power applications. Moreover, the current levels can be tailored to the needs of a specific circuit by simply changing the electrode area. We exploit the analog behavior of this new bilayer GaOx/HfO2 memristive device to detect high frequency activity of neuronal cell culture. The device response under pre-recorded neuronal signals (spike trains) is studied and shows a potential for integration in the back-end-of-line of hybrid CMOS/microelectrode array (MEA) chips for real-time neuronal activity processing.

Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Project MEMMEA (Project number 441918103) within the DFG SPP 2262 MemrisTec (Project number 422738993).

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