Temperature-dependent current conduction of metal-ferroelectric (BiFeO3)-insulator (ZrO2)-Silicon capacitors for nonvolatile memory applications

Metal-ferroelectric-insulator-semiconductor structures with BiFeO3 as the ferroelectric layer and zirconium oxide ZrO2 as the insulator layer were fabricated by RF magnetron sputtering. The plasma condition was varied with different argon to oxygen (Ar/O2) ratio. The sizes of memory window as functions of Ar/O2 ratio and postannealing temperature were investigated. The dominant conduction mechanism is Schottky emission and the reflective index (n) is calculated to be from 4.31 to 2.51 in the temperature range of 300 to 425 K under positive bias. However, the electrical conduction is dominated by Poole-Frenkel emission and the effective trap barrier height is about 0.65 eV under negative bias. The effect of surface roughness on the electrical conduction has been studied.