Defects Motion as the Key Source of Random Telegraph Noise Instability in Hafnium Oxide

Besides standard two- and multi-level Random Telegraph Noise (RTN), more complex cases of RTN are commonly reported which show peculiar current signal instabilities. The physical origin of such phenomena is typically traced back to the presence of metastable defects states, the Coulomb interaction between traps, and the possible interaction of hydrogen species with oxide defects. However, the effect of the motion of atomic species on RTN phenomena has never been brought to the picture, even though such a mechanism is extremely relevant for oxygen ions in HfO2, e.g., it guarantees resistive switching in HfO2 RRAM. In this paper, we demonstrate that complex RTN signals observed in experiments naturally emerge when considering the combination of the Coulomb field due to the trapped charge at defects together with their field-assisted motion. Strikingly, we demonstrate that multilevel RTN signals with high instability and complex time evolution, which are conventionally though to be caused by an intricate many-bodies problem involving several defects, can in fact result by the