EPIR effect of Cu2O films by electrochemical deposition

• EPIR effect was observed in the Cu/Cu2O/Cu/FTO device.
• The EPIR effect is closely related to the pH value prepared the sample.
• Weakly alkaline preparation solution can improve Cu2O films crystallization.
• Alkaline preparation solution will weaken the EPIR effect of Cu2O films.

Cuprous oxide (Cu2O) films and Cu/Cu2O/Cu/FTO sandwich structures were prepared by electrochemical deposition on conductive FTO substrates with different pH value conditions but constant deposition potential. The phase composition, crystal structure and microstructure of the Cu2O films were characterized by XRD, SEM and EDS as well as by Electric–Pulse–Induced–Resistance (EPIR) perturbation. In particular, the switching effects of the Cu/Cu2O/Cu/FTO device are examined in this work. The result shows that the EPIR-effect is large for the Cu/Cu2O/Cu/FTO device at room temperature and strongly related to the pH value of the solution. In both acidic and neutral conditions, for example at pH = 5, 6 and 7, the EPIR effect is significant and decreases with increasing pH value. It disappears when the pH value goes further into the alkaline regime, i.e. pH = 8, 9 and 10. Space charge barriers at the interface of electrode and Cu2O are used to explain the I–V characteristic of the layer structure and the EPIR-effect.