Resistive switching effect of HfO2/Nb:SrTiO3 under the influence of nanodefects and varying atmospheric conditions

Single-crystal Nb:SrTiO3 (NSTO) exhibits unique properties of high stability, excellent electrical conductivity, and atomic-level surface roughness, which makes it an important material for constructing oxide electrodes. In this work, an NSTO single-crystal substrate was irradiated with gallium ions in an ion beam system to introduce nanoscale surface defects, and weakly crystalline HfO2 films were deposited on the substrate to form HfO2/NSTO structures. The resistive switching (RS) effect of the unirradiated and irradiated HfO2/NSTO structures was studied. It was found that the HfO2/NSTO structures, both irradiated and nonirradiated, exhibit obvious RS characteristics. The presence of nanoscale defects on the surface of irradiated NSTO causes a local electric field distortion, resulting in the HfO2/NSTO structure exhibiting a lower set voltage and a superior RS performance compared to the nonirradiated HfO2/NSTO structure. Additionally, the RS characteristics of the samples under different atmospheric conditions were also investigated. A decrease in oxygen pressure facilitates the formation of oxygen vacancies, thereby reducing the set voltage and promoting the RS effect. However, excessively low oxygen pressure can lead to a shortage of oxygen ions, resulting in a lower resistance ratio between the high resistive and low resistive states. The samples obtained under oxygen pressures of 102 and 103 Pa exhibited optimal RS performance.