Electrode Defects in Multilayer Capacitors Part I: Modeling the Effect of Electrode Roughness and Porosity on Electric Field Enhancement and Leakage Current

Abstract

Multilayer capacitors consist of multiple, often hundreds of capacitors connected in parallel to maximize volumetric efficiency. As the dielectric and electrode layer thicknesses are scaled down, microstructural imperfections become increasingly influential on the device electrical performance. Specifically, the presence of nonplanar and discontinuous electrodes can lead to local field enhancements while the relative morphologies of two adjacent electrodes determine variations in the local dielectric thickness. To study the effects of electrode morphologies, an analytical approach is taken to calculate the field enhancement and leakage current with respect to an ideal parallel‐plate capacitor. It is shown that the electrode roughness causes the leakage current to increase with respect to that of the ideal flat parallel‐plate capacitor. To further include the effects of local curvature on electric field enhancements, finite element methods are used to calculate field distributions within capacitor structures containing rough interfaces and porosity. In these simulations, the effects of electrode pore diameters, dielectric layer thickness, and the amplitude and wavelength of the electrode roughness are studied.

Thin‐Layered Cobalt‐Based Catalysts on Stainless‐Steel Microfibers for the Efficient Electrolysis of Water

“…It is hard to compare these ratios with a previous report, which used in situ X‐ray absorption spectroscopy (XAS) measurements, because of natural relaxation of the Co oxidation states of Co‐MF during the preparation of XPS measurements. However, the higher oxidation state of the thin Co‐OEC layer deposited on the SS‐MFs might be caused by the increased electric field in the porous 3 D network, consistent with the results in Figure c …”

“…These results confirm that the different LSV curves are not simply derived from the faster diffusion of Co 2+ ions to the SS‐MFs. The shifted onset potential suggests that the SS‐MFs gain a thermodynamic benefit from the increased local electric field in the porous network of the metal microfibers . This is very interesting, because the 3 D porous SS‐MFs do not only provide a higher surface area for the catalysts, but they can also initiate water oxidation at a reduced applied potential.…”

Electrode Defects in Multilayer Capacitors Part II: Finite Element Analysis of Local Field Enhancement and Leakage Current in Three‐Dimensional Microstructures

“…[11][12][13] However, these electrostatic simulations were carried out on two-dimensional (2-D) microstructures. [11][12][13] However, these electrostatic simulations were carried out on two-dimensional (2-D) microstructures.…”

“…13,25 With advances in computational power, image-based finite element modeling has evolved considerably over the last decade, so that it is now possible to incorporate precise 3-D features from a reconstructed microstructure into a model, on which various simulations can be carried out to give precise results. 13,25 With advances in computational power, image-based finite element modeling has evolved considerably over the last decade, so that it is now possible to incorporate precise 3-D features from a reconstructed microstructure into a model, on which various simulations can be carried out to give precise results.…”

Effect of Firing Rates on Electrode Morphology and Electrical Properties of Multilayer Ceramic Capacitors

“…demonstrated the dependence of leakage current on the metal–insulator interface morphology due to local electric field enhancements around roughness . In the past, some of these observations have been quantified by calculating the electric field distribution in the presence of electrode defects such as porosities and roughness . Both analytical and numerical approaches have revealed defects such as the sites of high‐local electric fields, which in turn gave rise to higher leakage currents.…”