Stabilization of negative capacitance in ferroelectric capacitors with and without a metal interlayer

Abstract

The negative capacitance operation of a ferroelectric material is not only an intriguing materials science topic, but also a property with important technological applications in nanoscale electronic devices.

Intrinsic Nature of Negative Capacitance in Multidomain Hf0.5Zr0.5O2‐Based Ferroelectric/Dielectric Heterostructures

“…We further investigated this interpretation of the experiments by using a numerical model based on the multidomain Landau, Ginzburg, Devonshire (LGD) equations for the ferroelectric dynamics. [ 31,47,48 ] For the purposes of this work the model was extended in order to deal with symmetric, metal‐insulator‐ferroelectric‐insulator‐metal stacks.…”

“…The total energy U T consists of three main components: [ 48 ] where the first term is related to the Landau polynomial, U W denotes the domain wall energy, and the electrostatic energy U ET includes the contributions describing the depolarization energy.…”

Modelling and design of FTJs as high reading-impedance synaptic devices

“…Our starting point is the multi-domain Landau, Ginzburg, Devonshire (LGD) model (Eq.1, i= 1, 2 • • • n D , with n D being the number of domains) for a MFIM capacitor presented in [6][7][8]. In Eq.1 α i , β i , γ i are the domain dependent ferroelectric anisotropy constants, C 0 =(C D +C F ), d is the side of the square domain, k and w are the coupling constant and the inter-domain region width for the domain wall energy (Fig.…”

“…In Eq.1 α i , β i , γ i are the domain dependent ferroelectric anisotropy constants, C 0 =(C D +C F ), d is the side of the square domain, k and w are the coupling constant and the inter-domain region width for the domain wall energy (Fig. 1(b)), while the capacitances C i,j provide a three dimensional description of the depolarization energy and obey the sum rules n D j=1 (1/C i,j ) [8]. At each time t and bias V T (t), Eq.1 provides all the domain polarizations P i (t), so that the dielectric, V D,i , and ferroelectric, V F,i , voltage drops are uniquely given by Eqs.2 [8].…”

Thermodynamic equilibrium theory revealing increased hysteresis in ferroelectric field-effect transistors with free charge accumulation

“…The importance of analyzing the appropriate thermodynamic potential cannot be understated: a thermodynamic equilibrium analysis based on an inappropriate potential is at risk of producing unphysical results. In the vast majority of works published today, the Gibbs free energy 21,[38][39][40][41][42][43][44] or (though less frequently) the Helmholtz free energy 27,45,46 is used. However, a formal justification has never been provided.…”