Epitaxial Single and Double Nanolayers of SnO2 and TiO2 for Resistive Gas Sensors
2013 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 5, 1648-1655 p.Article in journal (Refereed) Published
Rutile TiO2 (1 0 1) and cassiterite SnO2 (1 0 1) epitaxial single and double nanolayers, the latter stacked in either sequence, are atomic layer deposited on r-cut alpha-Al2O3(0 1 (1) over bar 2) substrates. Thickness of the layers is varied. Epitaxial quality of the films is characterized by X-ray diffraction (XRD), reflection high-energy electron diffraction, and transmission electron microscopy. In gas response measurements, as-grown films and the films coated with electron-beam evaporated Pt nanoclusters are exposed, at 350 degrees C, to H-2, CO, and CH4 diluted in air. In response to test gas concentrations of 30 parts per million (ppm), the films with a thickness of order of 10 nm exhibit, depending on the makeup and gas, as high as two- to five-fold decrease in the resistance. It is shown that the platinum surface catalyst is effective in accelerating the response and recovery processes. The transition times of the order of a few tens of seconds are observed. The results demonstrate the feasibility of gas sensing with single-crystal-like nanolayer films. Comparison of sensor characteristics of such quasi-2D nanostructures and the literature data relevant to individual nanowires, nanorods, and nanobelts, i.e., typical representatives of the quasi-1D structures, shows that, as to H-2, CO, and CH4, both structures are worthy competitors.
Place, publisher, year, edition, pages
2013. Vol. 13, no 5, 1648-1655 p.
Atomic layer deposition (ALD), epitaxy, nanostructuring, thin film sensors
Natural Sciences Engineering and Technology
Research subject Engineering Science with specialization in Materials Science
IdentifiersURN: urn:nbn:se:uu:diva-200048DOI: 10.1109/JSEN.2013.2238227ISI: 000317486700001OAI: oai:DiVA.org:uu-200048DiVA: diva2:622928