Analysis of Ti valence states in resistive switching regions of a rutile TiO2−x four-terminal memristive device. (20th April 2018) - Yamaguchi, Kengo
Abstract: We have performed Ti valence state analysis of our four-terminal rutile TiO2− x single-crystal memristors using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS). Analysis of Ti-L2, 3 edge EELS spectra revealed that the electrocolored region formed by the application of voltage includes a valence state reflecting highly reduced TiO2− x due to the accumulation of oxygen vacancies. Such a valence state mainly exists within ∼50 nm from the crystal surface and extends along specific crystal directions. These electrically reduced surface layers are considered to directly contribute to the resistive switching (RS) in the four-terminal device. The present results add new insights into the microscopic mechanisms of the RS phenomena and should contribute to further development and improvements of TiO2− x based memristive devices.