Double S‐Shaped Polarization – Voltage Curve and Negative Capacitance from Al2O3‐Hf0.5Zr0.5O2‐Al2O3 Triple‐Layer Structure. (21st December 2022) - Park, Hyeon Woo
Abstract: The negative capacitance (NC) effect, recently discovered in a fluorite‐based ferroelectric thin film, has attracted great attention as a rescue to overcome the scaling limitations of the conventional memory and logic devices of highly integrated circuits. The NC effect manifesting an S‐shaped polarization–voltage ( P–V ) curve is initially interpreted by a 1‐dimensional Landau Ginzburg Devonshire (LGD) model. However, a series of recent studies have found that this effect can also be explained by the inhomogeneous stray field energy (ISE) model. In this study, by extending the ISE model in the ferroelectric (FE)‐dielectric (DE) layered structure, an analytical model that considers the influence of the interfacial screening charge distribution is presented. This model showed that the NC effect in the FE‐DE heterostructure can be manifested in various forms other than a single S‐shaped P–V curve. In particular, a double S‐shaped P–V curve is expected from the fully compensated anti‐parallel domain structure, confirmed experimentally in the actual Al2 O3 /(Hf0.5 Zr0.5 )O2 /Al2 O3 triple‐layer structure. Furthermore, to reveal the origin of the double S‐shaped P–V curve, a multidomain LGD model is presented. It is confirmed that this phenomenon is attributed to the evolution of inhomogeneous stray field energy. Abstract : The inhomogeneous stray field energy model for the metal‐insulator‐ferroelectric‐insulator‐metal structure where the ferroelectric bound charge of the anti‐parallel domain structure is compensated by the symmetrical screening charges at the lower and upper interfaces (the schematics is shown in ToC Figure (a)) reproduces the various double S‐shaped polarization – voltage curves (shown in ToC figure (b)) depending on the compensation factor λ.