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Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ∼65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210–400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

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.

To date, several portable, wearable, and even implantable electronics have been incorporated into ultracompact devices as miniaturized energy-autonomous systems (MEASs). Electrostatic supercapacitors could be a promising energy storage component for MEASs due to their high power density and ultrashort charging time. Several dielectric materials, including ceramics, polymers, and glass, have been studied for energy storage applications. However, due to their large thickness (in micrometers or larger), these materials are inappropriate for use as nanocapacitors. Recently, ferroelectric and antiferroelectric fluorite-structured dielectrics (e.g., zirconia and hafnia) have been studied intensively for data storage and energy-related applications. Their nanoscale (nm) thickness makes these materials suitable for use as nanocapacitors in MEASs. This work reviews the energy storage properties of fluorite-structured antiferroelectric oxides (HfO2 and ZrO2), along with 3-D device structures, the effect of negative capacitance on the energy storage characteristics of fluorites, and the future prospects of this research field.