Electrical stressing of bilayer insulator HfO2/Al2O3 metal-insulator-insulator-metal (MIIM) diodes

Bilayer metal/insulator/insulator/metal (MIIM) diodes of HfO₂ and Al₂O₃ using asymmetric metal gates are investigated for their susceptibility to trap charge. Comparing the effects of constant current electrical stressing for varying thicknesses of insulators, the authors have formulated an adaptation of the Fowler-Nordheim derivative method such that an estimate of the charge centroid location can be obtained for bilayer insulators. In this work it has been found the addition of an HfO₂ layer into an Al₂O₃ MIM device leads to increased charge trapping and greater shifts in the I-V characteristic.