A capacitor can include a substrate having a first surface, a second surface remote from the first surface, and a through opening extending between the first and second surfaces, first and second metal elements, and a capacitor dielectric layer separating and insulating the first and second metal elements from one another at least within the through opening. The first metal element can be exposed at the first surface and can extend into the through opening. The second metal element can be exposed at the second surface and can extend into the through opening. The first and second metal elements can be electrically connectable to first and second electric potentials. The capacitor dielectric layer can have an undulating shape.