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.