Nanostructured SnO

This paper describes the morphology, stoichiometry, microstructure and gas sensing properties of nano clustered SnOx thin films prepared by Sn evaporation followed by the Rheotaxial Growth and Thermal Oxidation (RGTO) process. Electron microscopy was used to investigate, in detail, the evolution of the films as the oxidation temperature was increased. The results showed that the contact angle, perpendicular height, volume and microstructure of the clusters all changed significantly as a result of the thermal oxidation processes. Electron diffraction and X-ray photoelectron spectroscopy measurements revealed that after oxidation at a temperature of 600 oC, the Sn clusters were fully transformed into porous 3-dimensional polycrystalline SnO2 clusters. Based on these results, a prototype SnO2 sensor was fabricated and sensing measurements were performed with H2 and NO2 gases. At operating temperatures of 150 oC 200 oC the film produced measurable responses to concentrations of H2 as low as 600 ppm and NO2 as low as 500 ppb. The nanostructure of SnO2 films prepared from evaporated Sn 2 PACS CODES: 07.07.Df (Sensors), 36.40.-c (Atomic and molecular clusters), 81.07.-b (Nanoscale materials and structures: fabrication and characterization). The nanostructure of SnO2 films prepared from evaporated Sn 3