Enhanced resistive switching memory characteristics and mechanism using a Ti nanolayer at the W/TaO x interface

Enhanced resistive memory characteristics with 10,000 consecutive direct current switching cycles, long read pulse endurance of >10(5) cycles, and good data retention of >10(4) s with a good resistance ratio of >10(2) at 85°C are obtained using a Ti nanolayer to form a W/TiO x /TaO x /W structure under a low current operation of 80 μA, while few switching cycles are observed for W/TaO x /W structure under a higher current compliance >300 μA. The low resistance state decreases with increasing current compliances from 10 to 100 μA, and the device could be operated at a low RESET current of 23 μA. A small device size of 150 × 150 nm(2) is observed by transmission electron microscopy. The presence of oxygen-deficient TaO x nanofilament in a W/TiO x /TaO x /W structure after switching is investigated by Auger electron spectroscopy. Oxygen ion (negative charge) migration is found to lead to filament formation/rupture, and it is controlled by Ti nanolayer at the W/TaO x interface. Conducting nanofilament diameter is estimated to be 3 nm by a new method, indicating a high memory density of approximately equal to 100 Tbit/in.(2).