Deposition of vanadium (V) oxide thin films on nitrogen-containing self-assembled monolayers

Vanadium oxide films have been deposited from aqueous solutions at low temperature on different self-assembled monolayer- (SAM-) modified silicon surfaces. Primary, secondary, and tertiary amine and ammonium salt SAMs were made via in-situ transformations of bromide SAMs. The degree of surface charge of SAM was estimated by using X-ray photoelectron spectroscopy (XPS).; The forces between different nitrogen-containing SAMs and spherical zirconia particles were investigated by using atomic force microscopy (AFM). These results indicated the existence of a Stern layer, i.e. charge inversion, on the amine surface.; The crystal structure and chemical composition of the vanadium oxide films were characterized by X-ray diffraction (XRD), and XPS, respectively. The thickness of the vanadium oxide coatings was similar on 1°-, 2°-, and 3°-amine SAMs, but that on alkylammonium salt SAM was 3–4 times thicker. In all cases, V₂O₅·1.6H₂O formed first (in the first 24 h), then V₂O₅·H ₂O formed. The film growth rate showed two separate growth periods corresponding to the formation of these two phases.; Mixed-valence and mixed-phase vanadium oxide films could be achieved by controlling the deposition conditions, whose effect on the kinetics of film growth has also been studied. Films up to 80 μm thick on ammonium salt SAM and 16 μm thick on amine SAM were grown in 72 h.