Tantalum-based nanotube arrays via porous-alumina-assisted electrodeposition from ionic liquid: Formation and electrical characterization

Fabrication of tantalum-based nanotube arrays was accomplished via porous anodic alumina (PAA) assisted electrodeposition (ED). Mechanically stable, free-standing and spatially-separated TaxOy-nanotubes were electrodeposited potentiostatically at −1.4 V vs. Pt with a high uniformity and population density across the sample surface. [Display omitted] •TaxOy nanotube arrays were electrodeposited via a porous anodic alumina PAA template.•Coulometry was applied to estimate the end of the pores filling.•The nanoarray was semiconducting, by virtue of the Ta suboxides (XPS determination).•Electrical resistivity of nanotube arrays was determined by impedance spectroscopy.•Thermal I-V characterization and Schottky junction analysis was performed. Fabrication of tantalum-based nanotube arrays was accomplished via porous anodic alumina (PAA) assisted electrodeposition (ED). The ED was performed through a PAA template from a conductive bottom face. Mechanically stable, free-standing and spatially-separated TaxOy-nanotubes were electrodeposited potentiostatically at −1.4 V vs. Pt with a high uniformity and population density across the sample surface. The electrolyte employed a room temperature ionic liquid ([BMP]Tf2N) as a solvent. Some impurities in the tantalum pentoxide nanotubes resulted from this selection of solvent. Additionally, some tantalum suboxides with valencies lower than 5 were present. Structural defects, oxygen vacancies and impurities were expected, which might account for the high leakage current of the TaxOy-nanotubes. The nanotubes resistivity was analyzed by the impedance spectroscopy. Based on the magnitude of resistivity and its thermal behavior we could classify the TaxOy material as semiconducting. Development of three-dimensional (3D) tantalum and tantalum oxide nanostructures is of particular interest for potential applications in microelectronic devices with high surface-to-volume ratios, e.g., metal–insulator-metal (MIM) storage capacitors, electrochemical sensors and switching microdevices.