Current-Sweep Operation on Nonlinear Selectorless RRAM for Multilevel Cell Applications

Bilayer selectorless resistive random-access memories (RRAM) have been demonstrated by utilizing the intrinsic nonlinear resistive switching (RS) characteristics, without additional transistor or a selector integration. The bilayer structures, i.e. high-k layer/low-k layer stacks, are highly scalable while suppressing the sneak path currents (SPC) and reading error in the crossbar RRAM array. The nonlinearity (NL) modulation is also investigated by different operating schemes, and a multilevel cell application is demonstrated with the current-sweep method. The results provide additional insights into the development and optimization of bilayer selectorless RRAMs with high nonlinearity, good memory window, and low switching energy (∼ 40 pJ/bit), which enable the high-density storage and low-power crossbar array memory applications.