A semiconductor device is provided comprising a semiconductor substrate having
on its top a Thin Strain Relaxed Buffer. The Thin Strain Relaxed Buffer consists
of a stack of three layers of essentially constant Ge concentration. The three
layers include a first epitaxial layer of Si1-xGex, a second
epitaxial layer of Si1-xGex:C, and a third epitaxial layer
of Si1-xGex on the second epitaxial layer. A method to fabricate
such a buffer is also provided.
