HfO2–Al2O3 Dielectric Layer for a Performing Metal–Ferroelectric–Insulator–Semiconductor Structure with a Ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 Thin Film

Abstract

In this work, the ferroelectric and fatigue characteristics of Au/0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3(BCZT)/Si metal–ferroelectric–semiconductor (MFS) structures are investigated. Moreover, the effect of introducing a thin dielectric HfO2–Al2O3 (HAO) layer with different thicknesses between the BCZT layer and the Si substrate on the ferroelectric characteristics in the metal–ferroelectric–insulator–semiconductor (MFIS) configuration is evaluated. It is evidenced that the insertion of the HAO layer with a thickness of 8 nm improves the memory window of the capacitance–voltage (C–V) curves by 106% compared to the value obtained in the MFS structure and reduces the leakage currents. Furthermore, the Au/BCZT/HAO (8 nm)/Si structure shows a remarkable remnant polarization (Pr) of 7.8 μC/cm2, with a coercive voltage of 1.9 V. The obtained value for Pr corresponds to a six times enhancement when compared to the value obtained in the Au/BCZT/Si structure. In addition, the fatigue studies reveal that the Pr obtained in the Au/BCZT/HAO/Si structure slightly decreases (3%) with continuous cycling, up to 109 cycles. The present work evidences that Au/BCZT/HAO/Si structures are promising for nonvolatile memory applications.