1. A memory device, comprising: a first electrode spaced from an underlying semiconductor substrate by dielectric; a second electrode over the first electrode, and spaced from the first electrode by ion conductive material; the ion conductive material comprising one or more compositions selected from the group consisting of chalcogenides and oxides; a pair of source/drain regions extending into the semiconductor substrate adjacent the first electrode, one of the source/drain regions being along one side of the first electrode and the other of the source/drain regions being along another side of the first electrode; and wherein at least one of the first and second electrodes has an electrochemically active surface directly against the ion conductive material.