Effect of p-n interface on resistive switching of NiO/CeO2 thin films

To investigate how the p−n interface affects the resistive switching, we studied bilayer and nanocomposite films composed of p−type NiO and n−type CeO2. The samples were fabricated on ITO substrate by sol−gel spin coating. The current-voltage curves were measured with GaIn liquid top electrode, which exhibit reversible bipolar resistive switching with the maximum ON/OFF ratio of ∼103 at a read voltage of +0.5 V. The ON/OFF ratio of bilayer samples is three times improved than that of the nanocomposite film. This is ascribed to the larger depletion width in bilayer film than that of the nanocomposite one. We show that the p−n structure plays a key role in the formation/rupture of filamentary paths due to different depletion interfaces of the films.