Post-breakdown conduction instability of ultrathin SiO2 films observed in ramped-current and ramped-voltage current-voltage measurements

Ramped-current and ramped-voltage current-voltage (I-V) measurements were carried out to investigate the conduction in ultrathin SiO2 films after breakdown, and all the I-V characteristics were plotted on a log-log scale to examine the power law behavior. In most cases, the conduction was stable, and the two measurements yielded identical I-V characteristics. However, in some cases, two phenomena exhibiting instability, i.e., the current switching and voltage switching between two well-defined states. were observed in the ramped-voltage and ramped-current measurements, respectively. For both the stable conduction with a single conduction state and the unstable conduction which involved different states. a linear relationship was observed in the log-log scale I-V characteristics for each state. indicating that each state followed a power law. The conduction instability is explained by a model based on the percolation concept.