Structural and optical characterization of WO3 thin films for gas sensor applications -: art. no. 093527

The structure, chemical composition, and optical properties of tungsten trioxide thin films grown by pulsed laser deposition were investigated. An ultraviolet KrF* excimer laser (lambda=248 nm, tau(FWHM)congruent to 20 ns, nu=2 Hz) was used for irradiation of tungsten trioxide targets in oxygen atmosphere. Our research focused on the effect of the ambient gas pressure and substrate temperature on the chemical composition, crystalline status, and optical properties of the obtained thin films. To this end, the films were studied by x-ray diffractometry Raman spectroscopy, and energy dispersive x-ray spectroscopy. Optical transmittance measurements were performed with a double beam spectrometer within the 400-1200 nm range. The films deposited at oxygen pressure values higher than 10 Pa and substrate temperatures above 300 degrees C consist of crystalline tungsten trioxide. Their average transmittance in the visible-infrared spectral region reaches about 85% appropriate for the envisaged applications. (C) 2005 American Institute of Physics.