Specific Quasi-Stable Nanostructure and Electron Transport Properties of Perovskite Thin Films

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Electron-transport mechanisms of oxide ceramics exhibiting high-speed voltage-pulse-induced resistivity changes were characterized with regard to nanostructure and defect formation. La-doped SrTiO_3 single crystals with Ag top electrodes and Pt bottom electrodes exhibited bipolar resistive switching but retained the low-resistivity state for only 3 or 4 hours because of unstable deep-level trap states at the metal-semiconductor interface. Crystalline (Pr^(0.7)Ca^(0.3)) MnO_3 thin films sandwiched by Pt electrodes showed metallic conductivity and consequently never showed electric-pulse-induced resistivity changes, but insulative amorphous (Pr^(0.7) Ca^(0.3)) MnO_3 thin films showed monopolar resistivity switching that suggested the formation of nanoscale filament paths with nanodomain switches. The TiO_2 anatase nanolayer formed on a TiN thin film exhibited high-speed electric-pulse-induced bipolar resistivity changes thought to be due to a Mott transition caused by O^(2-) migration and the formation and annihilation of Vo-in 2.5-nm-thick anatase layer.