Memristive switching in porous-alumina-assisted TiO2 nanocolumn arrays

abstract

English

Porous-anodic-alumina- (PAA-) assisted anodizing of valve metals like Ta, Nb, W, and Ti has been used for the formation of self-organized nanocolumn arrays of the corresponding metal oxide, vertically grown on a substrate and of various geometrical parameters [1]. On the way of exploring functional properties of PAA-assisted metal oxides (e.g. gas sensing, photoelectrochemical water splitting), a fundamental knowledge has recently been obtained of their electrical behavior, including resistive switching phenomena in the tungsten-oxide nanoarrays [2]. In the present work, we reveal, for the first time, the effect of memristive switching in TiO2 nanocolumn arrays grown via PAA-assisted anodizing of Ti layer prepared by magnetron sputtering. The TiO2 nanocolumn arrays were fabricated from Al (500 nm) on Ti (200 nm) layers, by anodizing the Al layer at 40 V resulting in formation of a PAA overlayer followed by re-anodizing of the Ti underlayer to 100 V resulting in ~150 nm long TiO2 nanocolumns embedded in the PAA matrix (Fig. 1a). The arrays were then annealed to alter their electrical properties. For electrically contacting the tops of the columns, a patterned layer of gold was either electrodeposited or sputtered over the sample. The Ti underlayer served as a bottom electrode (Fig. 1a). By measuring I(V) characteristics, electrical properties of the nanoarrays were obtained, and a correlation with the annealing conditions was revealed. The arrays grown at certain conditions showed noticeable resistive switching behaviors (Fig. 1b), manifested by a ratio of the resistivities in their high- and low-resistance state of 10 to 1000. The process appeared to be dependent on the anodizing variables, taking place either at the top or bottom oxide/metal interface.

anodic films, resistive switching, nanostructured titania, porous anodic alumina

BENDOVÁ, M.; MÁRIK, M.; MOZALEV, A.

11. 7. 2017

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