Reactive direct current magnetron sputtered TiO 2 thin films with amorphous to crystalline structures

Abstract

TiO 2 thin films were deposited on soda–lime glass substrates by reactive direct current magnetron sputtering in a mixture of pure argon and oxygen. The influence of both the deposition time, t d, and the post-annealing treatments on the films morphology, composition and structure was analyzed by scanning electron microscopy, ellipsometry, X-ray photoelectrons spectroscopy, X-ray diffraction (XRD) and Raman spectroscopy. Amorphous TiO 2 was obtained for the shortest deposition time, t d = 15 min. Increasing t d up to 30 min, poorly crystallized anatase and rutile phases were formed together with amorphous TiO 2, as was revealed by complementary XRD patterns and Raman spectra. For longer t d, the growth of the anatase phase dominates that of the rutile phase. The post-annealing treatment of the films in air at 450 °C. induced the complete crystallization of the films leading to mainly anatase films for all the deposition times. All these results show the feasibility to fabricate stoichiometric TiO 2 thin films with amorphous to crystalline structures by means of soft fabrication conditions: low substrate temperature and moderate annealing treatment.