Development of porous metal oxide thin films by co-evaporation

This paper focuses on the development of mixed metal oxide thin films and physical characterization of the films. The films were produced by co-evaporation of titanium oxide and tungsten oxide powders. This allowed the development of titanium oxide–tungsten oxide films as analyzed using XPS. Examination in the SEM and AFM showed that the films were nanoporous with the pore size and pore orientation varying as a function of the deposition angle. UV–vis spectra of the films show an increase of transmittance with increasing deposition angle which is attributed to the structure and porosity of the films. Raman analysis indicated that the as-deposited films have broad and weak Raman characteristics, attributed to the nanocrystal nature of the films and the presence of defects, and the peak broadening deceases after annealing the film, as expected.