SiGe strain relaxed buffer for high mobility devices and a method of fabricating it

摘要

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 Si_1-xGe_x, a second epitaxial layer of Si_1-xGe_x:C, and a third epitaxial layer of Si_1-xGe_x on the second epitaxial layer. A method to fabricate such a buffer is also provided.