The impact of oxygen vacancy defect density on the nonlinearity and short-term plasticity of TiO2-based exponential selector

The readout margin of the one selector-one RRAM crossbar array architecture is strongly dependent on the nonlinearity of the selector device. In this work, we demonstrated that the nonlinearity of Pt/TiO2/Pt exponential selectors increases with decreasing oxygen vacancy defect density. The defect density is controlled by modulating the sputtering pressure in the oxide deposition process. Our results reveal that the dominant conduction mechanisms of the Pt/TiO2/Pt structure transit from Schottky emission to Poole-Frenkel emission with the increase of sputtering pressure. Such transition is attributed to the rise of oxygen vacancy concentration. In addition, the short-term plasticity feature of the Pt/TiO2/Pt selector is shown to be enhanced with a lower defect density. These results suggest that low defect density is necessary for improved exponential selector performances.

Automated summary

The readout margin of the one selector-one RRAM crossbar array architecture is strongly influenced by the nonlinearity of the selector device. This study demonstrates that the nonlinearity of Pt/TiO2/Pt exponential selectors increases with decreasing oxygen vacancy defect density. The researchers found that the conduction mechanisms transition from Schottky emission to Poole-Frenkel emission with an increase in sputtering pressure, attributed to the rise in oxygen vacancy concentration. Additionally, the short-term plasticity feature of the Pt/TiO2/Pt selector is enhanced with a lower defect density.