“…Numerous approaches, including special surface treatment (Xie et al ., 1985 ), strained superlattices (Masafumi et al ., 1989 ;Samonji et al ., 1996 ), low-temperature buffers (Nozawa and Horikoshi, 1991 ) and growth on patterned substrates (Yamaichi et al ., 1994 ), have been employed to reduce the dislocation density to around 10 5 -10 6 cm − 2 , still two orders of magnitude higher than the typical number (<10 4 cm − 2 ) in InPor GaAs-based epitaxial wafers for room-temperature cw lasers. Recent advanced epitaxial techniques with SiGe (Groenert et al ., 2003a(Groenert et al ., , 2003b and GaSb (Cerutti et al ., 2010 ) buffer layers have enabled GaAs-based cw diode lasers on Si substrate at room-temperature. Decent performance of InGaAs quantum dot lasers on Si has been demonstrated by utilizing GaAs buffer layer and quantum dot as dislocation fi lters (Mi et al ., 2006 ).…”