The Cu-doped and undoped HfO2 films were fabricated and the effect of Cu doping concentration on resistive switching (RS) of HfO2 film was demonstrated. The X-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical bonding states of Cu in HfO2:Cu film. The improved RS behaviors in terms of ON/OFF ratio and switching parameters were observed for Cu-doped HfO2 film with bipolar resistive switching (BRS) behavior. With the increase of Cu doping concentration, the 9.7% Cudoped HfO2 film showed both BRS and unipolar resistive switching (URS) behaviors with large operating voltages. The space charge limited current (SCLC) effect was proposed to interpret the switching mechanism of HfO2: Cu films with BRS behavior and the URS behavior can be explained by the migration of Cu ions. (C) 2015 Elsevier B.V. All rights reserved.