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 1/f(gamma) behavior, with gamma = 1 in the ohmic region and with gamma = 3/2 at high bias beyond the ohmic region. The exponent gamma = 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 1/f noise in thin films has an estimated value of 10(-21) cm(2)/Omega, which is typical for metals or doped semiconductors. This value in combination with the low diode current indicates that the 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.