Theoretical studies of metal | transition metal dichalcogenides| metal vertical stacks: atomristors

Abstract :
Since the discovery of graphene and technologies to fabricate it, the share of 2D materials in nanotechnologies has consequently increased in the past few years [1,2]. In the 2D material family, transition metal dichalcogenides (TMDs) exhibit a resistive switching behaviour [3-5] in metal|TMD|metal vertical stacks, which would allow a switching time for radio-frequency switches of less than 10fs [6], when nowadays switches have a value ten times greater [7]. While the migration of metallic ions forming filaments in metal|hBN|metal systems has been found to be the main source of switching [8], no such claim has yet been made using TMDs. A recent theoretical study [4] using Au electrodes has shown that the creation of a half filament is enough to trigger the low-resistance state (LRS), while a full filament would require a vast amount of energy to form. The presence of defects affects little the high resistance state (HRS), but does provide a higher probability of creating such a half filament.
Using density-functional theory and non-equilibrium Green’s functions, this thesis concentrates on understanding the mechanisms of this switching in TMD systems, changing the electrode materials as well as the nature and phase of the TMDs in question. A database of devices with possible electrodes made of Au, Ag, Cu, Ni, Pt and TiN and mono , bi , tri layered TMDs {Mo;W}{S;Se;Te}2 is being built in order to establish a precise comparison of the HRSs and LRSs. Additional systems including hBN and graphene have also been investigated as possible footstones.
This presentation will mainly focus on the density functional theory and the non-equilibrium Green’s function method, to finish with some of the results that have been found.

References :
[1]    W. Cao et al., IEEE Trans. Electron Devices, 65 (2018) 4109
[2]    E. G. Marin et al., IEEE Trans. Electron Devices, 65 (2018) 4167
[3]    I. M. Datye et al., Nano Lett., 20 (2018)1461
[4]    X.-D. Li et al., Nanotechnology, 34 (2023) 205201
[5]    R. Ge et al., Nano Lett., 18(2018) 434
[6]    M. Kim et al., Nat. Commun., 9 (2018) 2524
[7]    F. Gianesello et al., 2016 IEEE 16th Top. Meet. Silicon Monolith. Integr. Circuits RF Syst. SiRF, (2016) 9
[8]    Y. Shi et al., Nat. Electron., 1 (2018) 458

Acknowledgements :
This work is supported by the ANR SWIT Grant (ANR-19-CE24-0004). It is implemented using HPC resources from GENCI–IDRIS (Grant 2023 A0140914157) and the GRICAD infrastructure (https://gricad.univ-grenoble-alpes.fr), which is supported by Grenoble research communities.