Enhanced Stochasticity in Irradiated Vanadium Oxide Oscillators

ABSTRACT

Insulator‐to‐metal transition (IMT) materials are highly sensitive to even minute deviations of stoichiometry, lattice defects, and disorder, which provides opportunities to engineer their electrical switching characteristics. Using vanadium oxide as a prototypical IMT resistive switching material, we demonstrate that focused ion beam irradiation induces stochastic oscillatory dynamics in simple two‐terminal switching devices. After irradiation, we observed an unusual dynamic regime where the voltage‐induced metallic state momentarily collapses into an insulating state, which results in rapid current flickering that is qualitatively different from the conventional current spiking in a Pearson‐Anson‐type oscillatory circuit implemented using the pristine material. Furthermore, the current flickering timing in the irradiated devices becomes progressively more random and sparser with increasing input voltage, resulting in nonlinear and nondeterministic oscillatory behavior. The irradiation also leads to a dramatic reduction in switching power required to induce the oscillations. These results are elucidated through random resistor network simulations, which indicate that a small number of local sites can control the electrical IMT switching properties in large devices with high defect concentration. Our results show that selective focused ion beam irradiation provides exciting prospects for engineering novel stochastic behaviors in emergent technologies that rely on intrinsic randomness of physical processes.