Spectroscopic Properties of WO3 Thin Films: Polarized FT-IR/ATR, X-Ray Diffraction, and Electronic Absorption

Abstract
The Fourier transform infrared/micro-attenuated total reflectance (FT-IR/mATR), X-ray diffraction (XRD), and electronic absorption properties of thin tungsten oxide films are characterized. Thin films of tungsten oxide (100–500 Å) deposited on SiO2 exhibit a different orientation or structure than thicker films. A p-polarized longitudinal optical (LO) mode at 970 cm−1 occurs in all ATR spectra of WO3 thin films and is one of the strongest IR bands in the spectra. The spectroscopic properties of tungsten oxide films are characterized as a function of substrate and heat treatment.