We lowered the crystallization temperature of amorphous TiO2 thin films using a Cu catalyst as either a bottom or cap layer. The Cu bottom layer reduced the crystallization temperature of TiO2 by similar to 30 degrees C. Depth profile analyses by Rutherford backscattering spectrometry revealed that a very small amount of Cu was sufficient to induce full crystallization of the TiO2 film. Depositing the Cu cap layer and annealing at 210 degrees C for 3 h yielded a transparent anatase TiO2 thin film upon wet-etching the Cu cap. (C) 2013 Elsevier B. V. All rights reserved.