A method for forming a nanowire device comprises depositing a hard mask on portions of a silicon substrate having a orientation wherein the hard mask is oriented in the direction, etching the silicon substrate to form a mandrel having (111) faceted sidewalls; forming a layer of insulator material on the substrate; forming a sacrificial stack comprising alternating layers of sacrificial material and dielectric material disposed on the layer of insulator material and adjacent to the mandrel; patterning and etching the sacrificial stack to form a modified sacrificial stack adjacent to the mandrel and extending from the mandrel; removing the sacrificial material from the modified sacrificial stack to form growth channels; epitaxially forming semiconductor in the growth channels; and etching the semiconductor to align with the end of the growth channels and form a semiconductor stack comprising alternating layers of dielectric material and semiconductor material.