Increase of capacitance of thick dielectrics by fringe effect

Abstract

For a capacitor with defined geometry, dimensions, and dielectric material, the capacitance normally cannot be changed. In this work, we found the apparent capacitance can be significantly increased by adding one or more electrodes to the lateral surfaces of dielectric materials, especially for the materials with large thickness/width ratio. The increase of capacitance is attributed to the capacitance formed by the small gaps between the lateral and top or bottom electrodes, which can response to the applied field due to the fringe effect. For a capacitor with thick dielectric material, the capacitance of the fringe capacitors, which are in parallel to the capacitor formed between the top and bottom electrodes, can be larger than the capacitance without lateral electrode, and increases the apparent capacitance.