Atomic layer deposition (ALD) of thin films from TiCl4 and O-3 on Si(100) substrates was investigated. The growth of TiO2 was obtained at substrate temperatures of 225-600 degrees C from these hydrogen-free precursors. Formation of anatase phase in the films was observed at 250-600 degrees C. In addition, the rutile phase was revealed in thicker films deposited at 600 degrees C. Compared to the well studied TiCl4-H2O ALD process the TiCl4-O-3 process allowed higher growth rate at 275-600 degrees C. In addition, relatively low surface roughness was obtained for thicker (>50 nm) films of the anatase structure deposited from TiCl4 and O-3 at 350-400 degrees C. Therefore TiCl4 and O-3 appeared to be a good precursor combination for ALD of TiO2, particularly for applications that require low concentration of hydrogen contamination. (C) 2013 Elsevier B.V. All rights reserved.