The exposure effect of the reaction surface to ultraviolet (UV) light was studied for atomic layer deposition (ALD) of TiO2 films from Ti((OPr)-Pr-i)(4) and H2O at 260 degrees C. UV light was irradiated on the reaction surface after the purge step of Ti-precursor and oxygen source, respectively. UV irradiation on the reaction surface resulted in a higher growth rate of the TiO2 films compared to the thermal ALD. The growth rate of anatase TiO2 increased by a factor of 2 to about 0.25 nm/cycle while the surface roughness was reduced. UV-light induced increase of the number of chemisorption sites is discussed as the possible mechanism. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3534833] All rights reserved.