Formaldehyde sensing mechanism of SnO2 nanowires grown on-chip by sputtering techniques
| Autor: | Sara Morandi, J. Samà, Albert Romano-Rodriguez, J. Gonzalez-Chavarri, Gemma García Mandayo, E. Castaño, I. Castro-Hurtado |
|---|---|
| Přispěvatelé: | Universitat de Barcelona |
| Rok vydání: | 2016 |
| Předmět: |
Materials science
General Chemical Engineering Nanowire chemistry.chemical_element Nanotechnology 02 engineering and technology 010402 general chemistry 01 natural sciences chemistry.chemical_compound Sputtering Chemical Engineering (all) Thin film High-resolution transmission electron microscopy Thermal oxidation business.industry Tin dioxide Chemistry (all) Nanostructured materials General Chemistry 021001 nanoscience & nanotechnology 0104 chemical sciences Band bending chemistry Optoelectronics Materials nanoestructurats 0210 nano-technology business Tin |
| Zdroj: | Recercat. Dipósit de la Recerca de Catalunya instname Dipòsit Digital de la UB Universidad de Barcelona |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c5ra26105h |
| Popis: | Tin dioxide nanowires have been grown by thermal oxidation of sputtered thin films by means of a VLS method. A tin sputtered layer catalyzed by gold nanoparticles acts as a material seed for the localized growth of NWs directly on gas sensor devices, avoiding the manipulation and transport of the nanowires to the electrodes. XRD and HRTEM analysis show that the nanowires crystallize in a rutile structure with a [100] preferential growth direction, and are single-crystalline with diameters lower than 50 nm. The response of nanowires to formaldehyde has been compared to thin film based sensors. A sensitivity of 0.10 ppm−1 is reported, twofold the sensitivity of the thin film, and short response and recovery times are measured (6 times shorter than thin films). The sensing mechanism proposed for the SnO2 NWs under formaldehyde exposure is explained by means of conduction measurements and FT-IR analysis. Oxygen species chemisorbed on the surface of each SnO2 nanowire produce a band bending, which generates a potential barrier (of 0.74 ± 0.02 eV at 300 °C) between the point contact of different nanowires. As evidenced by IR spectroscopy at 300 °C, electrons in the conduction band and in mono-ionized oxygen vacancies (at 0.33 eV below the bottom of the conduction band) are responsible for gas detection. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|