Atomic defect structure and electron transport property of high-speed resistivity-changing nanoceramics

Abstract

Electron-transport mechanisms of oxide ceramics exhibiting high-speed voltage-pulse-indueed resistivity changes were characterized with regard to nanostructure and defect formation. La-doped SrTiO3 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 h because of unstable deep-level trap states at the metal-semiconductor interface. Crystalline (Pr0.7Ca0.3) MnO3 thin films sandwiched by Pt electrodes showed metallic conductivity and consequently never showed electric-pulse-induced resistivity changes, but insulative amorphous (Pr0.7Ca0.3)MnO3 thin films showed monopolar resistivity switching that suggested the formation of nanoscale filament paths with nanodomain switches. The TiO2 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 o2- migration and the formation and annihilation of V..o in 2.5-nm-thick anatase layer.