US Patent 7105393 Strained silicon layer fabrication with reduced dislocation defect density

A strained silicon layer fabrication employs a substrate having successively formed thereover: (1) a first silicon-germanium alloy material layer; (2) a first silicon layer; (3) a second silicon-germanium alloy material layer; and (4) a second silicon layer. Within the fabrication each of the first silicon-germanium alloy layer and the second silicon-germanium alloy layer is formed of a thickness less than a threshold thickness for dislocation defect formation, such as to provide attenuated dislocation defect formation within the strained silicon layer fabrication.