Characterization of low-frequency noise in the resistive switching of transition metal oxide HfO ₂

Low-frequency noise measurements were performed on HfO ₂-based bipolar resistive switching memory devices. A 1/fα DC noise power spectral density was observed with α ∼ 1 for a low resistance state and α ∼ 2 for a high resistance state. We developed an electron tunneling model to elucidate the conduction process, which showed that the 1/fα behavior was due to the distribution of relaxation times of electron tunneling between the electrodes and the traps in the conducting filaments. The transition of the slope index α from 1 to 2 at a certain cutoff frequency indicates that there is a tunneling gap formed between electrodes and the residual of the conductive filaments in the high resistance state.