The effect of Cu doping concentration on resistive switching of HfO₂ film

Graphical abstract: - Highlights: • The Cu doped and undoped HfO₂ films were fabricated. • The improved RS behaviors were observed for Cu doped HfO₂ film with BRS. • The 9.7% doped HfO₂:Cu film showed both BRS and URS behaviors. • The related switching mechanisms were illustrated. - Abstract: 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% Cu-doped 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