Two Coexisting Pathways to Volatility in Valence‐Change Memory Devices

ABSTRACT Volatile valence‐change memory (VCM) devices are key building blocks for neuromorphic hardware, yet the physical origin of their volatility, whether ionic or electronic, remains debated. Here, we show that their post‐SET current relaxation is predominantly governed by ionic processes, while distinct electronic transients arise from a previously overlooked mechanism intrinsic to highly doped oxide Schottky junctions. To disentangle these contributions, we introduce a deep‐level‐transient‐spectroscopy‐inspired (DLTS) technique, Tunnel‐DLTS, employing sub‐ionic, low‐voltage pulses (0.3 V) over 15–450 K. We observe purely electronic responses exclusively under negative bias and within specific temperature windows consistent with activation energies of oxygen‐vacancy‐related electron traps. Dynamic Schottky‐barrier simulations incorporating tunneling and Shockley–Read–Hall dynamics reveal that these electronic transients emerge from the slow formation and relaxation of a quasi‐Fermi level, which we identify as a universal feature of nanoelectronic devices relying on highly doped oxide Schottky junctions. Together, these results establish two coexisting pathways to volatility: ionic decay and electronic transients, which paves the way for neuromorphic circuits that exploit tunable dual‐volatility within a single memristive device.