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

Mun Yin Chee; Putu Andhita Dananjaya; Gerard Joseph Lim; Calvin Xiu Xian Lee; Lingli Liu; Wen Siang Lew

doi:10.1088/1361-6528/acda40

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

Nanotechnology. 2023 Jun 19;34(36). doi: 10.1088/1361-6528/acda40.

Authors

Mun Yin Chee¹, Putu Andhita Dananjaya¹, Gerard Joseph Lim¹, Calvin Xiu Xian Lee¹, Lingli Liu¹, Wen Siang Lew¹

Affiliation

¹ School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.

PMID: 37257436
DOI: 10.1088/1361-6528/acda40

Abstract

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.

Keywords: 1S1R; RRAM; TiO2-based selector; oxygen vacancy; short-term plasticity.