Dynamics of Multi-Domains in Ferroelectric Tunnel Junction

TL;DR

This paper investigates how multidomain dynamics in ferroelectric tunnel junctions influence electrostatics and quantum transport, revealing oscillatory behaviors and local variations in tunneling electroresistance, and proposes optimization strategies for device performance.

Contribution

It introduces a 2D analytical model linking domain dynamics with electrostatics and quantum transport in FTJs, including effects of bottom insulator layers.

Findings

ON/OFF current density varies locally within the ferroelectric.

Device electrostatics and transport exhibit oscillatory behavior due to domain textures.

Approximate one-decade variation in local current density affects TER oscillations.

Abstract

The Discovery of giant tunnel electroresistance (TER) in Ferroelectric Tunnel Junction (FTJ) paves a futuristic possibility of utilizing the FTJ as a bistable resistive device with an enormously high ON/OFF ratio. In the last 20 years, numerous studies have reported that the formation of multidomain in ferroelectric material is an inevitable process to minimize the total system energy. Recent studies based on phase-field simulations have demonstrated that domain nucleation/motion substantially alters the electrostatics of a ferroelectric material. However, the impact of domain dynamics on quantum transport in FTJ remains elusive. This paper presents a comprehensive study of multidomain dynamics in a ferroelectric tunnel junction. Analysis of this article is twofold; firstly, we study the impact of domain dynamics on electrostatics in an FTJ. Subsequently, the obtained electrostatics is used to study the variations in tunneling current, and TER originated from multidomain dynamics. We show that ON/OFF current density and TER vary locally in the ferroelectric region. Furthermore, the device's electrostatics and quantum transport exhibit an oscillatory nature due to periodic domain texture. ON/OFF current density shows a sine/cosine distribution in ferroelectric, and approximately one-decade local variation in current density is observed. These local fluctuations in current density cause oscillations in the device's ON/OFF ratio. Optimization techniques to achieve a uniform and maximum TER are also discussed. A 2D analytical and explicit model is derived by solving coupled 2D Poisson's equation and Landau-Ginzburg equation. The model incorporates the switching and nucleation of domains by minimizing net ferroelectric energy (depolarization+free+gradient energy density). Furthermore, the impact of the bottom insulator layer on ferroelectric's gradient energy is also studied.