Enhanced resistive switching memory characteristics and mechanism using a Ti nanolayer at the W/TaO x interface
1 Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan
2 Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan
Nanoscale Research Letters 2014, 9:125 doi:10.1186/1556-276X-9-125Published: 17 March 2014
Enhanced resistive memory characteristics with 10,000 consecutive direct current switching cycles, long read pulse endurance of >105 cycles, and good data retention of >104 s with a good resistance ratio of >102 at 85°C are obtained using a Ti nanolayer to form a W/TiOx/TaOx/W structure under a low current operation of 80 μA, while few switching cycles are observed for W/TaOx/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 nm2 is observed by transmission electron microscopy. The presence of oxygen-deficient TaOx nanofilament in a W/TiOx/TaOx/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/TaOx 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.