ŠIMŮNKOVÁ Helena Brno University of Technology

Electrical Properties of Tantalum Nanotube Arrays prepared by Electrodeposition from Ionic Liquid

Co-authors KALINA Lukáš, BOUŠEK Jaroslav, MOZALEV Alexander

Electrodeposition (ED) of tantalum at a room or medium temperature (up to 200°C) using ionic liquids (ILs) has been a challenging process over the last decade. The success of first work on ED of Ta over a planar substrate [1] inspired us to advance the process striving to create an array of well aligned spatially ordered tantalum and tantalum oxide nanostructures via electrodeposition from IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, ([BMP]Tf2N) through nanopores in a thin-film alumina template (100-nm wide and 1-µm long pores of ~10^9 cm-2 population density) prepared by anodizing of aluminium on W/SiO2/Si substrate. Microscopically flat continuous Ta films (600 nm thick, well adherent to the substrate) and the free-standing arrays of Ta nanotubes filling the alumina pores were achieved via potentiostatic ED technique. XPS analysis revealed the presence of C, Ta, O, Li and F at least in the outer region of the electrodeposited coatings. The coatings annealed at 800°C at 10-5 Pa were fluoride- and lithium-free, and their surface region comprised Ta2O5(~67at.%), Ta2O, Ta and tantalum carbide (~33at.% in total). The I-V characteristics measured across the alumina-templated Ta nanotube array revealed a bipolar resistive switching event in the film, when the film behavior changes abruptly and reversely from a high resistance state (4 GΩ cm2) to a low resistance state (78 kΩ cm2) in a low voltage range. ACKNOWLEDGEMENTS: This research was supported in part by project CZ.1.07/2.3.00/30.0039 of BUT, by GAČR grant no.14-29531S and by project CZ.1.05/2.1.00/01.0012. LITERATURE: [1] N. Borisenko et al., Electrochimica Acta 54 (2009) 1519-1528