Resistive Switching Behaviour and Spiking Time Dependent Plasticity of PLD Grown VO₂/TiO₂ Thin Films Supplemented by Discrete Wavelength of Light

Electronic computing is undergoing a paradigm shift with the advent of neuromorphic architecture from the archetype von Neuman architecture. In neuromorphic architecture [1], data processing occurs within the storage memory, eradicating the data latency period. The overall data processing speed reduces acutely, further decreasing energy costs. A memristor is a highly scalable fundamental circuit component that switches across multiple stable states [2] at a very low energy cost, deeming it suitable for neuromorphic application. Transition metal oxides (TMOs) are suitable materials for the fabrication of these memristive components [3] showcasing resistive switching due to physiochemical mechanisms based on ion migration, electrolyte gated, phase change, ferroelectric, spintronic, photonic migration, electronic migration, and metal-insulator transition. Owing to the abundance of materials showing MIT for vested interest of neuromorphic application VO₂ shows MIT at near room temperature [4]. VO₂ undergoes a transition from the low-temperature monoclinic (M1) phase to the tetragonal (R) phase at a temperature above 68 ^○C, along with the occurrence of several unstable phases during the transition. The transition temperature of VO₂ can also be tuned to a higher or lower value under the effect of tensile or compressive strain in the lattice under the influence of an electric field, magnetic field, and the illumination of a specific wavelength of light [5]. VO₂/TiO₂ memristor fabricated using pulsed laser deposition, when illuminated with a laser source of 405 nm, 532 nm, 633 nm, and 980 nm, shows changes in memristive properties like R_OFF/R_ON ratio and switching power. In order to concretize the functioning of the memristor as an artificial synapse, spiking time-dependent plasticity (STDP) analysis [6] is performed under different illumination conditions to boot.<br/><br/><b>References</b><br/>[1] C. Mead, <i>Proc. IEEE</i> 78, 1629–1636 (1990).<br/>[2] L. Chua, <i>IEEE Trans. Circuit Theory</i> 18, 507–519 (1971).<br/>[3] A. Rana, C. Li, G. Koster, and H. Hilgenkamp, <i>Sci. Rep</i>. 10, 2–7 (2020).<br/>[4] U. Chitnis, S. Kumar, S. A. Bukhari, C. Soren, R. K. Ghosh and A. Goswami, <i>Appl. Surf. Sci</i>. 637, 157916 (2023).<br/>[5] G. Li, D. Xie, H. Zhong, <i>Nat. Commun.</i> 13, 1729 (2022).<br/>[6] R. Naik B., D. Verma and V. Balakrishnan, <i>Appl. Phys. Lett</i>. 120 (6) (2022).