Enhancing metal-insulator-insulator-metal tunnel diodes via defect enhanced direct tunneling

Abstract

Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al2O3-Ta2O 5 bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta2O 5 via defect based conduction before tunneling directly through the Al2O3, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature. © 2014 AIP Publishing LLC.