Formation of p-n junctions in nanoparticle cerium oxide electrolytic cells displaying memristive switching behaviour

A macro-scale metal-semiconductor-metal device comprising CeO₂ nanoparticles cast from a suspension of cerium dioxide formed by a novel synthetic method was fabricated. Thin CeO₂ films of 40 nm thickness placed between panels of aluminium and/or copper displayed memristive-like resistive switching behaviour upon the application of potential sweeps ranging between -0.6 V and 0.6 V. A mechanism is proposed based on the notion that an electrolytic cell operates under such conditions with the initial formation of p and n-type regions within the central semiconductive thin film. Evidence is presented for the existence of numerous point defects in these nanosized CeO₂ films, which are also likely to play a role in the device's operation acting as internal dopants. Steady currents were observed upon the imposition of constant potentials, most notably at higher potential values (both anodic and cathodic). It is suggested that electrons and holes act as charge carriers in these devices rather than ionic species as proposed in some other mechanisms.