Publication Informations

A systematic study of the nitridation of SnO2 nanowires grown by the vapor liquid solid mechanism
Authors: Matthew Zervos; Andreas Othonos
Year: 2012
Research Area: Nanowire synthesis
Type of Publication: Article
Journal Details
Journal: Journal of Crystal Growth
Volume: 340
Number: 1
Pages: 28 - 33
ISSN: 0022-0248
Keywords: Oxides
SnO2 nanowires (NWs) with diameters of 50 nm and lengths ≥10 μm have been grown at 800 °C on 1.0 nm Au/Si(001) via the vapor liquid solid mechanism and the low pressure chemical vapor deposition. These exhibited clear peaks in the X-ray diffraction corresponding to the tetragonal rutile crystal structure of SnO2 and a broad-symmetric photoluminescence (PL) spectrum, centered around 560 nm due to structural-related defect states, energetically located in the upper half-band-gap of SnO2. We find that post-growth thermal annealing of the SnO2 NWs over a broad range of temperatures, i.e. 400–1000 °C and high flow of O2 does not change their crystal structure or optical properties. In contrast the nitridation of SnO2 NWs using NH3 leads to their elimination above 500 °C. Lower temperatures did not favor the nitridation even using extended nitridation times, hydrogen, lower ramp rates or a two-step-temperature process which are effective in the case of In2O3 and Ga2O3. However the nitridation of SnO2 NWs was promoted by HCl, supplied in-situ via the sublimation of NH4Cl, which reacts with Sn and SnO2 leading to the formation of the intermediate SnCl4, which reacts in turn with NH3 giving tin nitride at temperatures between 400 and 500 °C . We discuss the effect of the nitridation and thermal annealing on the PL spectra.
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