FinFETs strained areas and methods for their preparation

A component comprising a substrate and dielectric regions over a portion of the substrate. A first semiconductor region is disposed between the non-conductor regions and consists of a material having a first conduction band. A second semiconductor region is over and disposed adjacent to the first semiconductor region, said second semiconductor region includes an upper portion which is positioned higher than top surfaces of the non-conductor portions to form a semiconductor rib. The second semiconductor region also comprises a wide portion and a narrow portion across the wide portion, the narrow portion is narrower than the wide portion. The semiconductor fin has a tensile stress and is made of a material having a second conduction band, which is arranged lower than the first conduction band. A third semiconductor region is disposed above and adjacent to a top surface and side walls of the semiconductor fin, wherein the third semiconductor region is made of a material which is located higher than the second conduction band a third conduction band.