Microcapacitors for Energy Storage: General Characteristics and Overview of Recent Progress

Abstract

Autonomous sensor systems and networks are of increasing demand toward the realization of the Internet of Things (IoT). In this respect, integrated devices for energy storage and management, such as microcapacitors and microbatteries, are intensively studied. Their integration with Si electronics is highly desirable, as it offers important advantages related to fabrication simplicity and cost reduction. Moreover, microcapacitors as compared with microbatteries offer additional advantages, including a theoretically infinite number of charge/discharge cycles, which makes them more appropriate for truly autonomous systems. They thus constitute the focus herein. Their basic characteristics for use in energy storage are discussed, and their interdependence is demonstrated, along with the demonstration that those characteristics cannot be independently optimized for energy storage. The two types of existing microcapacitors, namely the solid‐state microcapacitors and the microsupercapacitors, are presented in terms of their fabrication and integration schemes and their energy‐storage characteristics. Their advantages and disadvantages for the specific applications are analyzed. The usefulness of solid‐state microcapacitors in the above application, despite their significantly lower capacitance density compared with microsupercapacitors, is demonstrated, attributed to their integration maturity with standard complimentary metal‐oxide‐semiconductor (CMOS) processing, in addition to their larger charging voltages and maximum frequencies of operation.

On‐Chip Direct Laser Writing of PAN‐Based Carbon Supercapacitor Electrodes

“…[4][5][6] Different classes of organic and inorganic DOI: 10.1002/marc.202100731 materials have been explored for carbonbased microsupercapacitors electrodes, with the aim of increasing the surface area to yield acceptable capacitance despite their small size. [7][8][9][10][11][12] However, fabrication techniques to produce the required electrode geometries are limited to off-chip methods. The solvents or high processing temperatures employed to obtain carbonized, conductive electrode material are incompatible with typical electronic chip materials.…”

The Growth, Composition, and Functional Properties of Self‐Organized Nanostructured ZrO2‐Al2O3 Anodic Films for Advanced Dielectric Applications

“…More generally, offering a wide variety of useful surface morphologies, crystal structures, interface features, and attractive physical and chemical properties such as large band gap, low interface state density, and excellent thermal stability, these oxides may serve as building blocks for electronic components or system parts such as various types of capacitors, energy storage and flash devices, metal‐oxide‐semiconductor devices, multilevel interconnections, or multifunctional protective coatings. [ 1,2 ] While Nb 2 O 5 , TiO 2 , or even HfO 2 films often exhibit semiconductive properties or readily allow dielectric‐to‐semiconductor transition, ZrO 2 seems advantageous in this regard because special efforts would be required to make the full zirconium oxide oxygen deficient and potentially semiconductive. Therefore, its stable chemical composition and stoichiometry, microstructure, relatively high permittivity (22–24), large band gap (≈5.8 eV), exceptional chemical and thermal stability, and reportedly good high‐frequency dielectric performance place ZrO 2 high up on the list of multipurpose dielectric applications.…”

“…Therefore, its stable chemical composition and stoichiometry, microstructure, relatively high permittivity (22–24), large band gap (≈5.8 eV), exceptional chemical and thermal stability, and reportedly good high‐frequency dielectric performance place ZrO 2 high up on the list of multipurpose dielectric applications. [ 2,3,4,5,6 ]…”

On-chip Direct Laser Writing of PAN-based Carbon Supercapacitor Electrodes

“…[4][5][6] Different classes of organic and inorganic 2 materials have been explored for carbon-based microsupercapacitors electrodes, with the aim of increasing the surface area to yield acceptable capacitance despite their small size. [7][8][9][10][11] However, fabrication techniques to produce the required electrode geometries are limited to off-chip methods. The solvents or high processing temperatures employed to obtain carbonized, conductive electrode material are incompatible with typical electronic chip materials.…”