Epitaxial growth of WO3films on SrTiO3and sapphire

Tungsten trioxide films were deposited on (100) SrTiO3 and R-plane (10 2) cut sapphire substrates by dc magnetron sputtering, using a tungsten target in an Ar/O2 sputtering gas mixture at substrate temperatures ranging from 500 to 850 °C. Deposited films were characterized by x-ray diffraction using -2 scans and pole figure analysis. X-ray results showed that films deposited on both types of substrate were epitaxial. The equilibrium phase was monoclinic -WO3 , confirmed by Raman spectroscopy. Films on both substrates were (001) oriented. This preferred orientation improved as the deposition temperature was reduced. The in-plane orientation relationship of the films with the substrate was obtained from the pole figures.