Study of the composition and structure of titanium dioxide based coatings deposited by the method of reactive magnetic sputtering
The present paper is aimed to study the structure and chemical composition of titanium dioxide films deposited in various regimes of reactive magnetron sputtering. A choice of parameters and regimes of sputtering influences the formation of titanium dioxide coatings with certain properties. The goal of this work was to carry out experimental studies to solve the problems associated with the effect of different parameters of sputtering on the structure, phase and elemental composition of titanium dioxide coatings deposited by the method of reactive magnetron sputtering. Using the method of X-ray phase analysis based on Sherrer's formula, the grain sizes of coatings under study have been determined. A technique of layer-by-layer measurement of combination scattering from nanostructured titanium dioxide films based on a preliminary atomization of the films by inert gas beams (in the present case argon) under an angle of 45° and less has been developed. The mechanism of a change of the combination scattering spectra shape at a change of magnetron sputtering parameters has been revealed. For instance, for samples deposited in the regime of a negative shift (-60 V) having the grain size of 13.6 nm the intensity of the Raman peak of optical phonons at the mode Eg1 (144 cm-1) is approximately ten times less, than for coatings obtained without a shift on the substrate (the grain size 8.2 nm). It has been shown that it is possible to control the grain size in coatings by changing the ratio between the supply of inert and active working gas components during sputtering and the values of voltage shift on substrate. The method of obtaining combination scattering spectra of nanostructured titanium dioxide is described. The method of X-ray phase analysis allowed determining the dominating phase of the titanium dioxide coatings, and the study of the morphology by means of scanning electron microscopy has shown that the coatings have fine-grained surfaces.