Variable conductivity of nanocomposite nickel oxide/porous silicon

Continuous-state variable conductivity of nickel oxide/porous silicon nanocomposite thin films indicative of memristance is reported and a mathematical model for the observed behavior is proposed. The variable conductivity phenomena observed are shown to depend on the composition of the films. A generalized composite material conductivity model that explains the time-varying, field-dependent conductivity modulation is developed based on ionic defect migration in the metal oxide nanocrystallites. The model shows excellent agreement with experimental data and allows for estimation of ionic defect mobilities. Multicycle nonvolatility in the devices is shown to be on the order of 1000 s. The tunable conductivity of the nanocomposite is potentially useful in the fabrication of large-scale or high-power analog circuit elements such as memristors, and provides insights into ionic defect migration properties in nanocomposite materials.