Structure and composition of thermally annealed Mo- and W-based CVD metal oxide thin films

Thin films of molybdenum, tungsten and mixed MoO3-WO3 oxides obtained by atmospheric pressure chemical vapor deposition (APCVD) are investigated by applying Raman and XRD measurements. All the films were prepared by identical technological parameters and were annealed at 400 °C. Analysis of the Raman and XRD spectra of the three types of films shows that molybdenum oxide films crystallize in orthorombic MoO3 with a small fraction of MoO2.89 sub-oxide, while the annealed tungsten oxide films are triclinic WO3 with less than 2% sub-oxide of W20O58. The Raman spectra of the mixed MoO3-WO3 films indicate crystalline phases of molybdenum and tungsten oxides in an amorphous framework. In addition, XRD results show that the structure of the mixed oxides follows the crystallization of WO3 and Mo atoms are suggested to be substitute of W in the WO3 lattice.