Resistive Switching in Platinum/Titanium Dioxide Schottky Diode

Noble metal contacts to metal oxides are required in fabrication of numerous electronic and optoelectronic devices, especially those operating at elevated temperatures and harsh conditions. Here, electronic features of a Pt/TiO₂/Ti structured device are investigated. The Ti/TiO₂ junction is prepared by controlled oxidation of a Ti thin film, previously deposited on a fused silica substrate. The Pt electrode is formed by evaporative deposition of the metal source in vacuum on the TiO₂surface. The device exhibits atmospheric sensitive I-V characteristics. Both the Pt/ and Ti/TiO₂ junctions have ohmic behaviour in the as-fabricated state of the device, while, its field-assisted heat treatment in air renders the Pt/TiO₂ junction Schottky. The effect is described based on adsorption of oxygen species to the device surface during the heat treatment process and, hence, compensation of oxygen vacancies in the metal/TiO₂interface. Nonvolatile resistive switching is observed in the heat-treated device at 1 Hz frequency, while at 5 Hz, the switching becomes volatile. Origins of this phenomenon are discussed considering the Schottky barrier at the Pt/TiO₂ junction and the motion of ionized oxygen vacancies in the device structure.