M. Utriainen et al., Controlled electrical conductivity in SnO2 thin films by oxygen or hydrocarbon assisted atomic layer epitaxy, J ELCHEM SO, 146(1), 1999, pp. 189-193
The conventional atomic layer epitaxy process for pure SnO2 thin films uses
SnCl4 and H2O as precursors and Np as the carrier gas. By applying gas-pha
se additives (n-hexane, ozone) or using oxygen as a carrier gas, a reduced
electrical conductivity of the solid was obtained. This phenomenon is assoc
iated with the modifications in the grain structure and/or in the point def
ect concentration. To verify this, structural studies by X-ray diffraction,
atomic force microscopy, Auger electron spectroscopy, and secondary ion ma
ss spectroscopy were performed. The results suggest that the variations in
electrical resistivity (0.1-89 Omega cm) are predominantly due to variation
s in the electronic carrier concentration, i.e., oxygen vacancy and/or chlo
rine-impurity concentrations, which were induced by gas-phase additives. Th
e most promising additive was hexane, as it resulted in SnO2 firms of the l
owest conductivity as well as the highest crystallinity and stoichiometry.
The strength of this effect was, however, dependent on the position of hexa
ne pulse in the pulsing sequence. (C) 1999 The Electrochemical Society. S00
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