Low-Frequency Diffusion Noise in Resistive-Switching Memories Based on Metal–Oxide Polymer Structure

Low-frequency noise is studied in resistive-switching memories based on metal–oxide polymer diodes. The noise spectral power follows a $\hbox {1}/f^{\gamma }$ behavior, with $\gamma = \hbox {1}$ in the ohmic region and with $\gamma = \hbox {3/2}$ at high bias beyond the ohmic region. The exponent $\gamma = \hbox {3/2}$ is explained as noise caused by Brownian motion or diffusion of defects which induce fluctuations in diode current. The figure of merit to classify $\hbox {1}/f$ noise in thin films has an estimated value of $\hbox {10}^{-21} \hbox {cm}^{2}/\Omega$ , which is typical for metals or doped semiconductors. This value in combination with the low diode current indicates that the $\hbox {1}/f$ noise is generated in the narrow localized regions in the polymer between the contacts. The analysis unambiguously shows that the current in bistable nonvolatile memories is filamentary.