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 ((Formula presented.) 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.