Benjamin Spetzler1,Dilara Abdel2,Zhansong Geng1,Frank Schwierz1,Patricio Farrell2,Martin Ziegler1
Ilmenau University of Technology1,Weierstrass Institute2
Benjamin Spetzler1,Dilara Abdel2,Zhansong Geng1,Frank Schwierz1,Patricio Farrell2,Martin Ziegler1
Ilmenau University of Technology1,Weierstrass Institute2
Two-dimensional (2D) layered transition metal dichalcogenides (TMDCs) are promising materials for memristive devices and have gained significant attention because of their potential use in neuromorphic computing systems. However, despite extensive experimental work (e.g., [1,2]), the underlying resistive switching mechanisms in 2D TMDCs are still not understood, impeding progress in material and device functionality. This study discusses the contributions of various mechanisms to the current-voltage hysteresis and switching dynamics in 2D TMDC materials in detail and reveals the dominant role of mobile point defects [3]. Here, the switching process is governed by the formation and annihilation dynamics of a local vacancy depletion zone. Moreover, minor changes in the interface potential barriers cause fundamentally different device behavior previously thought to originate from multiple mechanisms. The key mechanisms are identified with a numerical charge transport model for electrons, holes, and ionic point defects, including image-charge-induced Schottky barrier lowering, Joule heating, and charge trapping dynamics. The model is validated by comparing simulations with measurements for various 2D MoS<sub>2</sub>-based and HfS<sub>2</sub>-based lateral devices, which also allows us to identify the characteristic dynamic behavior as a fingerprint of the underlying physical mechanism. Our results strongly corroborate the relevance of vacancies in lateral TMDC devices and offer a new perspective on the switching mechanisms and the influence of Joule heating. The insights gained from this work can be used to extend the functional behavior of 2D TMDC memristive devices in future neuromorphic computing applications.<br/><br/>Funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–Project-ID 434434223–SFB 1461, the Carl-Zeiss Foundation via the Project MemWerk, and the Leibniz competition 2020 (NUMSEMIC, J89/2019) is gratefully acknowledged.<br/><br/>1. Bessonov, A.A.; Kirikova, M.N.; Petukhov, D.I.; Allen, M.; Ryhänen, T.; Bailey, M.J.A. Layered memristive and memcapacitive switches for printable electronics. <i>Nat. Mater.</i> <b>2015</b>, <i>14</i>, 199–204, doi:10.1038/nmat4135.<br/>2. Da Li; Wu, B.; Zhu, X.; Wang, J.; Ryu, B.; Lu, W.D.; Lu, W.; Liang, X. MoS<sub>2</sub> memristors exhibiting variable switching characteristics toward biorealistic synaptic emulation. <i>ACS Nano</i> <b>2018</b>, <i>12</i>, 9240–9252, doi:10.1021/acsnano.8b03977.<br/>3. Spetzler, B.; Abdel, D.; Schwierz, F.; Ziegler, M.; Farrell, P. The Role of Mobile Point Defects in Two-Dimensional Memristive Devices <b>2023</b>, doi:10.48550/arXiv.2304.06527.