• Mishra, Yogendra K.
• Lupan, Oleg
• Chow, Lee
• Adelung, Rainer
• Braniste, Tudor
• Sarua, Andrei
• Enachi, Mihail
• Tiginyanu, Ion
• Gedamu, Dawit

Abstract

<p>Titania (TiO₂) exists in several phases possessing different physical properties. In view of this fact, we report on three types of hydrogen sensors based on individual TiO₂ nanotubes (NTs) with three different structures consisting of amorphous, anatase or anatase/rutile mixed phases. Different phases of the NTs were produced by controlling the temperature of post-anodization thermal treatment. Integration of individual TiO₂ nanotubes on the chip was performed by employing metal deposition function in the focused ion beam (FIB/SEM) instrument. Gas response was studied for devices made from an as-grown individual nanotube with an amorphous structure, as well as from thermally annealed individual nanotubes exhibiting anatase crystalline phase or anatase/rutile heterogeneous structure. Based on electrical measurements using two Pt complex contacts deposited on a single TiO₂ nanotube, we show that an individual NT with an anatase/rutile crystal structure annealed at 650 °C has a higher gas response to hydrogen at room temperature than samples annealed at 450 °C and as-grown. The obtained results demonstrate that the structural properties of the TiO₂ NTs make them a viable new gas sensing nanomaterial at room temperature.</p>

Topics

• Deposition
• amorphous
• scanning electron microscopy
• nanotube
• crystalline phase
• Hydrogen
• focused ion beam