Aerosol-Assisted Chemical Vapor Deposition of Tungsten
Oxide Films and Nanorods from Oxo Tungsten(VI) Fluoroalkoxide Precursors
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Abstract
Aerosol-assisted chemical vapor deposition
(AACVD) of WO<sub><i>x</i></sub> was demonstrated using
the oxo tungsten(VI) fluoroalkoxide single-source precursors, WO[OCCH<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>]<sub>4</sub> and WO[OC(CH<sub>3</sub>)<sub>2</sub>CF<sub>3</sub>]<sub>4</sub>. Substoichiometric
amorphous tungsten oxide thin films were grown on indium tin oxide
(ITO) substrates in nitrogen at low deposition temperature (100–250
°C). At growth temperatures above 300 °C, the W<sub>18</sub>O<sub>49</sub> monoclinic crystalline phase was observed. The surface
morphology and roughness, visible light transmittance, electrical
conductivity, and work function of the tungsten oxide materials are
reported. The solvent and carrier gas minimally affected surface morphology
and composition at low deposition temperature; however, material crystallinity
varied with solvent choice at higher temperatures. The work function
of the tungsten oxide thin films grown between 150 and 250 °C
was determined to be in the range 5.0 to 5.7 eV, according to ultraviolet
photoelectron spectroscopy (UPS)
