Comparative Performance of Fluorite-Structured Materials for Nanosupercapacitor Applications

TL;DR

This study compares fluorite-structured materials for nanosupercapacitors, highlighting antiferroelectric ZrO2's potential for high energy density and efficiency, with AFE HfZrO2 films showing promising balanced performance.

Contribution

It provides a comparative analysis of ferroelectric, antiferroelectric, and linear dielectric fluorite materials, demonstrating the high energy storage and efficiency potential of AFE HfZrO2 thin films.

Findings

FE HfZrO2 achieves highest ESD but low efficiency.

LD samples have nearly 100% efficiency but lower ESD.

AFE ZrO2 balances ESD and efficiency, with potential for further improvement.

Abstract

Over the last fifteen years, ferroelectric and antiferroelectric ultra thin films based on fluorite-structured materials have drawn significant attention for a wide variety of applications requiring high integration density. Antiferroelectric $ZrO_2$, in particular, holds significant promise for nanosupercapacitors, owing to its potential for high energy storage density (ESD) and high efficiency ($\eta$). This work assesses the potential of high-performance $Hf_{1-x}Zr_{x}O_2$ thin films encapsulated by TiN electrodes that show linear dielectric (LD), ferroelectric (FE), and antiferroelectric (AFE) behavior. Oxides on silicon are grown by magnetron sputtering and plasma-enhanced atomic layer deposition. ESD and $\eta$ are compared for FE, AFE, and LD samples at the same electrical field (3.5 MV/cm). As expected, ESD is higher for the FE sample ($95 J/cm^3$), but $\eta$ is ridiculously small ($\approx$ 55%), because of the opening of the FE hysteresis curve inducing high loss. Conversely, LD samples exhibit the highest efficiency (nearly 100%), at the expense of a lower ESD. AFE $ZrO_2$ thin film strikes a balance between FE and LD behavior, showing reduced losses compared to the FE sample but an ESD as high as $52 J/cm^3$ at 3.5 MV/cm. This value can be further increased up to $84 J/cm^3$ at a higher electrical field (4.0 MV/cm), with an $\eta$ of 75%, among the highest values reported for fluorite-structured materials, offering promising perspectives for future optimization.