Engineering structural discontinuity in ordered Co3O4 nanocube arrays for volatile memristive dynamics
Abstract
The precise engineering of nanoscale gaps between discrete building blocks offers a direct pathway to govern charge transport physics in functional materials. Here, we demonstrate a fundamental transition from stochastic bulk conduction to reliable interface-mediated volatile switching by deliberately introducing structural discontinuity in spinel-type Co 3 O 4 nanocube (NC) arrays. While continuous oxide thin films suffer from irreversible breakdown and featureless transport, and disordered NC assemblies exhibit only leakage-like conduction, our self-assembled NC architecture enables a stable and low-power functional response. Utilizing an automated metrology framework based on the Segment Anything Model (SAM), we confirm the formation of a highly ordered, non-percolated square lattice with a narrowly distributed interparticle gap of 2.84 ± 0.64 nm across thousands of junctions. This statistically defined NC-gap-NC junction network confines the active conduction volume to nanoscale junctions, achieving an ultralow operating current of ~ 10 nA and exceptional statistical uniformity (coefficient of variation < 9%); the operating voltage is likewise set by the interparticle junction and can be brought to the ~ 1 V regime by contracting the gap through ligand exchange. Quantitative analysis identifies junction-limited, multi-regime transport across the NC-gap-NC interfaces as the dominant conduction picture, with Schottky-emission-like injection at intermediate fields and Fowler–Nordheim-type field-assisted tunneling at high fields. Furthermore, time-resolved measurements reveal dual-mode relaxation dynamics characterized by microsecond electronic detrapping and slow recovery consistent with ionic back-diffusion, which facilitate complex temporal dynamics for biomimetic signal processing. Our findings suggest that a preformed, statistically quantified nanogap network, rather than bulk percolation, can serve as a useful design principle for energy-efficient electronic primitives beyond conventional continuous media.