A structure includes a semiconductor fin on a substrate. A first fin transistor (finFET) is on the substrate, and a second finFET is on the substrate adjacent the first finFET. The first finFET and the second finFET include respective pairs of source/drain regions with each including a first dopant of a first polarity. An electrical isolation structure is in the semiconductor fin between one of the source/drain regions of the first finFET and one of the source/drain regions for the second FinFET, the electrical isolation structure including a second dopant of an opposing, second polarity. The electrical isolation structure extends to an upper surface of the semiconductor fin. A related method is also disclosed.