Methods of fabricating a semiconductor structure in which a body of monocrystalline silicon is formed on a sidewall of a sacrificial mandrel and semiconductor structures made by the methods. After the body of monocrystalline silicon is formed, the sacrificial material of the mandrel is removed selective to the monocrystalline silicon of the body. The mandrel may be composed of porous silicon and the body may be fabricated using either a semiconductor-on-insulator substrate or a bulk substrate. The body may be used to fabricate a fin body of a fin-type field effect transistor.