I have a problem bothering me for a long time. Here it is: suppose I have an asymmetrical parallel plate capacitor with one electrode much larger than the other. For example, the capacitor could be made by depositing small-area metal electrode on heavily doped wafer with 300 nm thermal oxide. Is there a way to calculate the fringe field component parallel to the SiO2 surface at the edge of the small metal electrode? A figure is attached to make the question clear. Thanks.