Abstract
In this study, the resistive switching scheme using TiO2 nanorod arrays synthesized by a large-scale and low-cost hydrothermal process was reported. Especially, the nonlinear I–V characteristics of TiO2 nanorod arrays with a nonlinearity of up to ~10, which suppress the leakage current less than 10−4 Acm−2, were demonstrated, exhibiting a self-selecting resistive switching behavior. It provides a simple pathway for integration of RRAM crossbar arrays without additional stacking of active devices. The mechanisms of the nonlinear resistive switching behaviors were discussed in detail. In addition, the maximum array numbers of 79 for self-selecting RRAM cells were estimated. The results demonstrate an opportunity of using the concept of self-selecting resistive switching characteristics in a single material, which offers a new strategy to tackle the sneak path issue of RRAM in the crossbar arrays structure.
Highlights
Among the emerging nonvolatile memory (NVM) technologies, resistive switching random access memory (RRAM) utilizing resistive switching (RS) phenomena is one of the most promising candidates for next-generation nonvolatile memory due to the simplest device structure, the fastest switching speed, the highest stacking density, the lowest power consumption, the largest scalability, the lowest fabrication process cost and the strongest potential for fabricating multistate memories[1,2,3,4]
For resistive switching characteristics measurements, a Pt thin film with a thickness of 100 nm as the top electrode was deposited on TiO2 nanorod arrays with ~700 nm in length by the rf-magnetron sputtering at room temperature while the fluorine-doped tin oxide (FTO) substrate was used as the bottom electrode (BE) as shown in inset of Fig. 2(a)
I–V characteristics of the Pt/TiO2 nanorod arrays (NRs)/FTO memory device were studied by DC voltage sweep measurements where the bias voltages were applied to the top electrode (TE) with the bottom electrode (BE) grounded, and the pristine device with a resistance of ~167 Ω from I–V curve was measured
Summary
Among the emerging nonvolatile memory (NVM) technologies, resistive switching random access memory (RRAM) utilizing resistive switching (RS) phenomena is one of the most promising candidates for next-generation nonvolatile memory due to the simplest device structure, the fastest switching speed, the highest stacking density, the lowest power consumption, the largest scalability, the lowest fabrication process cost and the strongest potential for fabricating multistate memories[1,2,3,4]. Passive crossbar arrays utilizing one diode-one resistor (1D1R)[12, 14, 15], one selector-one resistor (1S1R)[16, 17] or complementary resistive switches (CRS)[11, 18,19,20] with the I–V nonlinearity characteristics provide effective ways to overcome the sneak path issue. The promising material, such as VOx, with self-selecting resistive switching performance for crossbar memory arrays was demonstrated[35] Such unique property offers a simple way for practical application without additional device steak. Various TiO2 thin film devices have been widely evaluated as a resistive switching material for RRAM6, 7, 36, the resistive switching characteristics of TiO2 nanorod arrays (NRs) structure have seldom been discussed In this regard, the self-selecting resistive switching characteristics of TiO2 nanorod grown on a fluorine-doped tin oxide (FTO) by a hydrothermal method are investigated for the first time[37]. The concept of nonlinear I–V characteristics in single material offers the new strategy to overcome the sneak path problem in the crossbar arrays structure
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