A technique relates to a semiconductor device. A first epitaxial material is formed under a bottom surface of a set of fins, the first epitaxial material being under fin channel regions of the set of fins. A second epitaxial material is formed adjacent to the first epitaxial material and remote from the fin channel regions, a combination of the first epitaxial material and the second epitaxial material forming a bottom source or drain (source/drain) layer. A top source/drain layer is formed on an upper portion of the set of fins, gate material being disposed around the set of fins between the top source/drain layer and the bottom source/drain layer.