Controlling Memristive Switching Behavior of Sr₂TiO₄ Thin Films by Miscut Nb:SrTiO₃ Substrate

Local redox processes at the defect states in oxides are significantly affected by the presence of oxygen vacancies in the crystal lattice of the oxide materials. In this study, the effect of oxygen vacancy formation in Sr2TiO4 crystal structure is investigated by performing the resistive switching experiments as well as synaptic characterizations through the variation of the miscut angles of the substrates. On the basis of the switching performance, a clear bipolar resistive switching and excellent memristor properties are shown for the sample grown on a low (i.e., 1°) miscut angle substrate. However, for the sample grown on high (i.e., 2°) miscut angle substrate, the film becomes (i) two times more conducting, (ii) 1 order of magnitude lower filament resistance, and (iii) at least five times narrower current–voltage hysteresis window compared with the sample grown on 1° miscut angle. The statistical analysis and conduction mechanism suggest that this is due to the incomplete disruption of the conducting filament. These results propose that the local redox process in the film is correlated to the oxygen vacancy migration induced by the substrates. The work provides an insight into the mechanism of switching filament formation and rupture that is important for future resistive-switching devices.