Impact of the electrical initialization step on transition voltage and power of vanadium dioxide memristors

Vanadium dioxide (VO2) exhibits an insulator-to-metal transition (IMT) near room temperature. Toward its practical use as volatile memristors, we investigate the effect of the first electrical cycle (initialization) on the electrically activated IMT of VO2-based devices. We utilize polycrystalline VO2 thin films on SiO2 to fabricate micro-memristors with varying length (L = 0.6–2.4 μm) and width (W = 5–25 μm). They are analyzed as voltage-driven devices, systematically assessing the necessity of an initialization cycle to stabilize their behavior. The impact of the initialization is interpreted using a percolation model based on a stochastic 2D heterogeneous network. It demonstrates that the introduction of persistent metallic domains from the very first activation facilitates later switching events occurring at lower voltage. The voltage-induced transition was further studied across thirty memristors per layer, on two layers of differing quality (sixty devices in total), revealing that the initial electroforming-like event significantly reduces both the transition voltage (Vimt) and current (Iimt) required for subsequent transitions for all geometries. Notably, the transition power (Pimt) becomes geometry-independent and is reduced by up to 90% compared to the first activation. This study demonstrates, models, and assesses the impact of an initialization process in VO2-based memristors.