Abstract
The behavior of WO X resistive random access memory (ReRAM) is a strong function of the top electrode material, which controls the conduction mechanism and the forming process. When using a top electrode with low work function, the current conduction is limited by space charges. On the other hand, the mechanism becomes thermionic emission for devices with a high work function top electrode. These (thermionic) devices are also found to have higher initial resistance, reduced forming current, and larger resistance window. Based on these insights and considering the compatibility to complementary metal-oxide-semiconductor (CMOS) process, we proposed to use Ni as the top electrode for high performance WO X ReRAM devices. The new Ni/WO X /W device can be switched at a low current density less than 8 × 10 5 A/cm 2 , with RESET/SET resistance ratio greater than 100, and extremely good data retention of more than 300 years at 85 °C. © 2011 The Japan Society of Applied Physics.