Unipolar resistive switching of EuxOy polycrystalline films

Polycrystallized EuxOy thin films show unipolar resistive switching. The ratios of the resistance values of the high-resistance state to those of the low-resistance state are as large as 10(8). The deposited EuxOy thin films show mixed phases, Eu2O3 and Eu3O4. The relative concentration of the phases could be controlled by using the oxygen gas flow rate during growth. A high oxygen concentration leads to broadening the distribution of the switching voltages, inducing transitions between the high-resistance state and the low-resistance state. We observe that the distribution of the switching voltage from the high-resistance state to the low-resistance state (V-SET) is smaller than or comparable to that of the switching voltage inducing the opposite transition (V-RESET) in well-controlled EuxOy thin films.