Recent Progress on Energy-Related Applications of HfO₂-Based Ferroelectric and Antiferroelectric Materials

Abstract

Ferroelectric and antiferroelectric materials are promising options for energy-related (such as energy harvesting, energy storage, IR detection, and refrigeration) and memory applications (such as ferroelectric random-access memory (FeRAM) and ferroelectric field-effect transistor (FeFET)). In the past, several classes of materials (such as polymers, ceramics, single crystals, and glasses) have been studied for these properties. However, because of a large deposition thickness (in micrometers or larger), these materials are inappropriate for future nanoscale devices. Recently, the ferroelectric and antiferroelectric HfO2-based thin films have also been studied for the energy-related and memory applications. HfO2-based materials have many advantages over the conventional materials, such as compatibility with Si-based semiconductor technology, ultrasmall thicknesses (nm), and simple compositions, and they are appropriate for integration within 3-D nanostructures. HfO2-based materials can be promising for energy-related applications, such as energy storage, pyroelectric energy harvesting, IR sensors, and solid-state cooling. This article provides some basic knowledge of these energy-related properties. Moreover, this article reviews the energy-related properties of HfO2-based thin films, their origins, and the prospects of this research field.

Harnessing Phase Transitions in Antiferroelectric ZrO2Using the Size Effect

“…[1] AFEs are a unique class of materials which, due to their nonlinear dielectric and strain characteristics, are useful for energy storage, infrared sensing, active electronic cooling, piezoelectric devices, and electronic memories. [2][3][4] Double fluorite-structured materials based on DFT calculations as well as experimental evidence. [3,6,20,23] The stabilization of the FE o-phase has been the focus of many investigations due to the interest in using FE HfO 2 -based thin films for CMOS compatible memory applications, such as FE random access memory and FE field effect transistors.…”

“…[3,5] Underlying electric field-induced FE structural phase transitions are hypothesized to be responsible for generating the distinctive features of antiferroelectricity in the fluorite material system, yet little is known about how to best exploit such phase transitions in fluorites. [4,6] Alternative theories of AFE-like behavior, such as oppositely imprinted FE domains and paraelectric-to-paraelectric phase transitions, need to be evaluated since the approach to achieve superior AFE device performance will depend on the underlying cause of macroscopic antiferroelectricity. [7][8][9][10] Due to the simplicity of controlling the film thickness, the size effect may be easily leveraged to influence and gain a better understanding of antiferroelectricity in ZrO 2 , but previous film thickness studies on ZrO 2 and Hf 1−x Zr x O 2 have not quantified the size-effect influence on supercapacitor performance.…”

Microstructural evolution and ferroelectricity in HfO2 films

“…Similar temperatureinduced FE phase transformations were also reported in HZO solid systems and Al-doped HfO 2 films [20,74] . This phenomenon is very useful for energy-related applications in nanoscale devices, such as electrocaloric cooling devices [31,51,139,140] . Hoffmann et al [23] reported that giant pyroelectric coefficients up to 1300 μC/(m 2 K) were achieved due to the temperature-induced structural transition.…”

HfO2‐Based Ferroelectrics Applications in Nanoelectronics

“…[ 47 ] A recent review discussing the performances of energy conversion and their dependence on temperature and doping concentrations is ref. [48]. The energy storage density (ESD) is a parameter relevant for ferroelectric materials.…”

“…In ref. [48], it is noted that antiferroelectrics show a double hysteresis loop and lower losses compared to ferroelectrics, and thus attaining higher ESD.…”