A device includes a substrate and multiple wells formed over the substrate and isolated from one another by dielectric trenches. The device further includes multiple memory elements formed over the wells, each of the memory elements extending approximately perpendicular to the wells and including a material doped with n-type impurities. The device also includes multiple source/drain regions, each source/drain region formed within one of multiple trenches and inside one of the plurality of wells between a pair of the memory elements, each of the source/drain regions implanted with p-type impurities. The device further includes a first substrate contact formed in a first one of the multiple trenches through a first one of the wells into the substrate and a second substrate contact formed in a second one of the multiple trenches through a second one of the wells into the substrate.