Step tunneling enhanced asymmetry in asymmetric electrode metal-insulator-insulator-metal tunnel diodes

摘要

The impact of nanolaminate insulator tunnel barriers on asymmetric metal workfunction metal-insulator-insulator-metal (MIIM) devices is investigated. We demonstrate experimentally that bilayer insulators introduce additional asymmetry and can be arranged to either enhance or oppose the asymmetry induced by the asymmetric workfunction electrodes. It is also shown that step tunneling can dominate the Ⅰ-Ⅴ asymmetry of M_1IIM_2 diodes. By combining bilayer tunnel barriers with the standard approach of asymmetric metal electrodes, we are able to achieve low voltage asymmetry and non-linearity exceeding both that of standard single layer asymmetric electrode metal-insulator-metal devices as well as symmetric electrode M_1I_1I_2M_1 devices.