Role of Hydrogen Ions in TiO₂-Based Memory Devices

Abstract

Field-programmable rectification (FPR) and resistive switching in TiO ₂ are under investigation as bases for nonvolatile memory devices. It has been suggested that FPR results from the field-induced drift of mobile dopants, particularly oxygen vacancies. In this article, it is shown that hydrogen ions, not oxygen vacancies, are the mobile dopant responsible for FPR in the Pt/TiO ₂ /Pt system. In addition, it is shown that resistive switching and FPR are observable in the same device, with FPR existing prior to an electroforming step and resistive switching observed afterwards. This suggests that hydrogen might be a source of resistive switching as well.

Acknowledgments

Work on TiO₂ was carried out under the Nonvolatile Memory Technology Research Initiative (NMTRI) at Stanford University, supported by Texas Instruments, Intel, Applied Materials, Samsung, Toshiba, Panasonic, and Qimonda. Work on TiO₂ was performed at the Stanford Nanofabrication Facility of the National Nanotechnology Infrastructure Network, supported by the National Science Foundation under Grant ECS-9731293. SIMS measurements were performed by Evans Analytical Group, Sunnyvale, CA 94086.