NANOscientific

Investigation of resistive switching behavior of 2D Tellurium films using C-AFM

S. Ghomi^1,2, M. Gardella¹, C. Grazianetti¹, A. Molle¹ and C. Martella*¹

¹ CNR-IMM Agrate Brianza Unit, via C. Olivetti 2, Agrate Brianza, I-20864, Italy

2 Dipartimento di Energia, Politecnico di Milano; via Ponzio 34/3, I-20133 Milano, Italy

*christian.martella@cnr.it

The increasing demand for the development of memories with low operating voltage, compatible with CMOS technologies and simple structure, has brought the attention to the promising two-dimensional (2D) materials [1]. Novel 2D materials such as transition metal dichalcogenides and Xenes [2,3] have inspired new type of memory developments including resistive random-access memory (RRAM) devices working on non-volatile resistive switching (RS) between a high and a low resistance state [4]. In this work, we report on the observation of the RS behavior of 2D tellurium films directly deposited by vapor transport deposition (VTD) with optimized conditions on different conductive platforms such as tantalum nitride, single crystalline Au (111) / Mica and CMOS compatible platform polycrystalline Au / SiO₂ / Si (n⁺⁺) substrates which serve as bottom electrode. [5]

The RS behavior of VTD-grown tellurium with thickness variation from 5 to 15 nm was investigated by conductive atomic force microscopy (C-AFM) technique that uses a sharp conductive diamond coated tip which acts as the localized top electrode. Using C-AFM, it is possible to acquire the electrical and topographic properties of the sample simultaneously at the nanoscale. The RS behavior of tellurium films was revealed by performing point spectroscopy embedded in C-AFM, through applying the ramped voltage and measuring the current passing from the sample to the tip. In addition, further investigations were made in different configurations such as ultra-thin tellurium films transferred from insulating SiO2/Si substrate to Au (111) / Mica. These investigations highlight the beneficiary role of the direct VTD tellurium on gold platforms to establish an enhanced RS behaviour evidenced by reduction of set/reset voltages and the enhanced energy consumption. To complement the analysis, the structural and chemical characterizations of the tellurium films were performed using Raman spectroscopy, XPS and TEM. In addition, using finite element analysis a thermoelectric simulation was conducted to evaluate and compare the temperature distribution induced by Joule heating in vertical Te / Au stack.

This work has been financially supported by the European Commission under the H2020 ERC-COG grant n. 772261 “XFab” and MUR PRIN 2022  Project “mastering two-Dimensional matErialS featurIng shape enGineeriNg” (DESIGN) 2022EE8KH9.

References

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Nano Letters 2018 18 (1), 434-441

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[5] Ghomi S, Martella C, et al. ChemRxiv. 2024; doi:10.26434/chemrxiv-2024-l0q8c