Title :
The role of oxygen vacancies in the sensing properties of SnO2 nanocrystals
Author :
Epifani, Mauro ; Siciliano, Pietro ; Prades, J. Daniel ; Pellicer, Eva ; Cirera, Albert ; Morante, Joan R. ; Comini, Elisabetta ; Faglia, Guido ; Scotti, Roberto ; Morazzoni, Franca ; Avella, Manuel
Author_Institution :
Consiglio Naz. delle Ric., Ist. per la Microelettronica ed I Microsistemi, Lecce
Abstract :
SnO2 nanocrystals (6 nm) were prepared by a wet chemical route and heat-treated at 500degC. The nanocrystals were characterized by X-ray photoelectron spectroscopy, conductometric measurements and cathodoluminescence spectroscopy. The results, interpreted with the aid of molecular modeling carried out in the frame of the Density Functional Theory (DFT), indicated that the nanocrystals contain topographically well-defined surface oxygen vacancies. The NO2 adsorption properties of the oxygen vacancies, investigated by DFT modeling, indicated that the in-plane oxygen vacancies facilitate the NO2 adsorption at low operating temperatures, and that the bridging oxygen vacancies enhance the charge transfer from the surface to the adsorbate. Thus an actively transducing surface is obtained through generation of surface oxygen vacancies. If this enhancing phenomenon is complemented with the grain size effects, remarkable gas-responses can be obtained.
Keywords :
X-ray photoelectron spectra; adsorption; cathodoluminescence; density functional theory; electrical conductivity; gas sensors; grain size; molecular dynamics method; nanofabrication; nanostructured materials; semiconductor materials; tin compounds; vacancies (crystal); NO2 adsorption; SnO2; SnO2 nanocrystals; X-ray photoelectron spectroscopy; cathodoluminescence spectroscopy; charge transfer; conductometric measurements; density functional theory; grain size effects; molecular modeling; oxygen vacancies; sensing properties; size 6 nm; surface defects; temperature 500 degC; wet chemical route; Charge transfer; Chemicals; Density functional theory; Grain size; Nanocrystals; Nanostructured materials; Spectroscopy; Surface topography; Temperature; Tin;
Conference_Titel :
Sensors, 2008 IEEE
Conference_Location :
Lecce
Print_ISBN :
978-1-4244-2580-8
Electronic_ISBN :
1930-0395
DOI :
10.1109/ICSENS.2008.4716395
