A method of microfabrication includes providing a substrate having a first layer including a first semiconductor material. A second layer of a second semiconductor material is formed over the first layer. The second layer is directionally etched using a mask to form independent core structures of the second semiconductor material on the first semiconductor material. A third layer of a first dielectric material is formed on an exposed surface of the first layer to cover a lower portion of a respective sidewall of each core structure. A shell structure is formed on an upper portion of a respective sidewall of each core structure to form shell structures including at least one semiconductor material. The core structures are removed such that each shell structure forms a vertical semiconductor structure extending vertically from the first layer and electrically isolated from the first semiconductor material by the first dielectric material.