Forming Process Investigation of $\hbox{Cu}_{x} \hbox{O}$ Memory Films

The forming process, which is the first transition from fresh state to low resistance state, was investigated in CuxO memory films prepared by plasma-induced oxidation. X-ray photoelectron spectroscopy investigation of surface chemical bonds of CuxO films and Auger electron spectroscopy depth spectra show that the formation of a highly resistive CuO layer on the CuxO surface is the main reason for the requirement of a large forming voltage. After selectively deoxidizing the CuO into Cu2O, the need for the "forming" process disappears.