Voltage-Tunable Ultra-Steep Slope Atomic Switch with Selectivity over 1010

Abstract

Atomic switch-based selectors, which utilize the formation of conductive filaments by the migration of ions, are researched for cross-point array architecture due to their simple structure and high selectivity. However, the difficulty in controlling the formation of filaments causes uniformity and reliability issues. Here, a multilayer selector with Pt/Ag-doped ZnO/ZnO/Ag-doped ZnO/Pt structure by the sputtering process is presented. A multilayer structure enables control of the filament formation by preventing excessive influx of Ag ions. The multilayer selector device exhibits a high on-current density of 2 MA cm^-2 , which can provide sufficient current for the operation with the memory device. Also, the device exhibits high selectivity of 10¹⁰ and a low off-current of 10^-13 A. The threshold voltage of selector devices can be controlled by modulating the thickness of the ZnO layer. By connecting a multilayer selector device to a resistive switching memory, the leakage current of the memory device can be reduced. These results demonstrate that a multilayer structure can be used in a selector device to improve selectivity and reliability for use in high-density memory devices.

Keywords: Ag-doped ZnO; atomic switch; cross-point array; electrochemical metallization; selector devices.