Changes in the titanium oxide optical properties during crystallization

Abstract

Crystallization of amorphous titanium oxide films synthesized by magnetron sputtering was carried out at temperatures of 700, 800, and 900oC in an oxygen atmosphere. The refractive index of the films increases during crystallization with a time constant that depends on temperature, which made it possible to determine the activation energy of the crystallization process on the order of 0.6 eV. The growth kinetics model for the titanium oxide nanocrystals, which is used in this work, showed that the indicated activation energy corresponds to the diffusion energy of oxygen vacancies. This process is decisive for the growth of titanium oxide nanocrystals upon annealing in an oxygen atmosphere. The study of photoluminescence has shown that crystallization leads to a change in the ratio of intensities of different emission bands. The bands that are associated with the oxygen vacancy are extinguished. A decrease in the concentration of these vacancies in films leads to an increase in their resistance and stabilization of the films in time. Keywords: titanium oxide films, crystallization, refractive index, photoluminescence.