A semiconductor memory device is fabricated by forming an active region protruding from a semiconductor substrate, forming an isolation layer on the substrate adjacent opposing sidewalls of the active region, and forming a floating gate electrode on a surface of the active region between the opposing sidewalls thereof. The floating gate electrode is formed to extend beyond edges of the surface of the active region onto the isolation layer. A surface of the floating gate electrode adjacent the active region defines a plane, and the isolation layer is confined between the plane and the substrate. A control gate electrode is formed on a surface of the floating gate electrode opposite the active region. The control gate electrode may be formed to extend along sidewalls of the floating gate electrode towards the substrate beyond the plane defined by the surface of the floating gate electrode adjacent the active region. Related devices are also discussed.