Strained silicon

Strained silicon is a layer of silicon in which the silicon atoms are stretched beyond their normal interatomic distance. This can be accomplished by putting the layer of silicon over a substrate of silicon germanium (SiGe). As the atoms in the silicon layer align with the atoms of the underlying silicon germanium layer (which are arranged a little farther apart, with respect to those of a bulk silicon crystal), the links between the silicon atoms become stretched - thereby leading to strained silicon. Moving these silicon atoms farther apart reduces the atomic forces that interfere with the movement of electrons through the transistors and thus better mobility, resulting in better chip performance and lower energy consumption. These electrons can move 70% faster allowing strained silicon transistors to switch 35% faster.