Anna Varini | Searcharxiv

arXiv2026

Monolithically Integrated VO$_2$ Mott Oscillators for Energy-Efficient Spiking Neurons

Brain-inspired non-Boolean computing and sensing enable energy-efficient, error-tolerant, and highly parallel information processing, yet their deployment remains limited by the lack of compact, scalable spiking hardware. Mott phase-transition materials offer a promising route because their abrupt insulator-to-metal transitions enable neuron-like thresholding and oscillations. Among them, vanadium dioxide (VO$_2$) is particularly attractive owing to its near-room-temperature transition, fast switching, and scalability. However, existing VO$_2$ neuristors rely on discrete components, limiting integration density. Here, we report monolithic back-end-of-the-line (BEOL) integration of one-transistor-one-VO$_2$-memristor (1T-1MR) spiking neurons on a CMOS-compatible platform. VO$_2$ nanosheets are fabricated by pulsed-laser deposition atop dielectrically isolated silicon-on-insulator (SOI) p-type junctionless field-effect transistors (JLFETs) below 430 $^\circ$C. The architecture exhibits gate-tunable oscillations from 40 to 410 kHz in 60 nm-thin VO$_2$ devices with a 6 $\mu$m$^2$ active area, achieving 18 pJ per spike and 8 $\mu$W at room temperature, with potential for sub-3 $\mu$W operation. We uncover a non-monotonic dependence of oscillation frequency on bias current and temperature and analyze bias-dependent stochastic firing, revealing the nonlinear physics of integrated VO$_2$ thin-film memristors. Finally, we demonstrate voltage-controlled oscillator functionality and on-chip resistive coupling between two nano-oscillators mediated by a JLFET. These results establish a pathway toward dense, energy-efficient, monolithically integrated Mott neuromorphic hardware compatible with future computing and spiking sensing systems.

eess.SY↗

arXiv2025

CMOS-compatible vanadium dioxide via Pulsed Laser and Atomic Layer deposition: towards ultra-thin film phase-change layers

Vanadium dioxide, a well-known Mott insulator, is a highly studied electronic material with promising applications in information processing and storage. While fully crystalline layers exhibit exceptional properties, such as a sharp and abrupt conductivity change at the metal-insulator transition, fabricating poly-crystalline films on silicon substrates often involves trade-offs in transport characteristics and switching performance, especially for ultra-thin layers required in advanced gate applications. In this study, we explore the growth of vanadium dioxide films on standard wet-oxidized silicon wafers using two established deposition techniques with pulsed laser deposition and atomic layer deposition. Thin films, ranging in thickness from 200 to 10 nano meters, were systematically characterized through structural and electrical analyses to optimize key growth parameters. Temperature and pressure were identified as the primary factors affecting film quality, and the optimal growth conditions across the entire thickness range are discussed in detail. We demonstrate that both pulsed laser deposition and atomic layer deposition methods can successfully produce ultra-thin vanadium dioxide layers down to 8 nano meters with functional properties suitable for practical applications. This work underscores the potential of vanadium dioxide for fully industry compatible phase-change switching devices and provides valuable insights into optimizing growth processes for poly-crystalline films.

cond-mat.mtrl-sci↗