Large 1/f noise of unipolar resistance switching and its percolating nature

We investigated the 1/f noise of Pt/NiO/Pt capacitors that show unipolar resistance switching. When they were switched from the low to high resistance states, the power spectral density of the voltage fluctuation was increased by approximately five orders of magnitude. At 100 K, the relative resistance fluctuation SR/R2 in the low resistance state displayed a power law dependence on the resistance R: i.e., SR/R2∝Rw, where w=1.6±0.2. This behavior can be explained by percolation theory; however, at higher temperatures or near the switching voltage, SR/R2 becomes enhanced further. This large 1/f noise can be therefore an important problem in the development of resistance random access memory devices.