Lateral conduction switching in sputtered Ni-rich NiO thin films for write-once-read-many-times memory applications

Magnetron sputtering has been used to deposit Ni-rich nickel oxide thin films. Based on the switching of lateral current conduction in the nickel oxide thin film between two in-plane electrodes, a planar write-once-read-many-times memory device has been demonstrated. The switching from a low-conductance state (i.e., the OFF state) to a high-conductance state (i.e., the ON state) is induced by a writing voltage, and it is irreversible due to the formation of tilted conductive filaments that are hard to be dissolved by the Joule heating effect. For 80 devices under test, the writing voltage is in a narrow range of 2.0-3.5 V and the ON/OFF resistance ratio is larger than 10⁵ at the reading voltage of 0.3 V. An excellent reading endurance (10⁶ readings) for both ON and OFF states is demonstrated. The device is promising in low-power applications as it can operate at ultra-low voltages (e.g., the reading voltage can be below 100 mV).