Optimized M BE out gassing procedures eliminated Hillock-type oval defects, allowing the bonding of epitaxial GaAs/ AlGaAs wafers with Si wafers. The application of a single growth epitaxial structure for the fabrication of laser diode (LD) and photodetector (PD) devices was investigated. Four graded index separate confinement heterostructure-multiquantum well (GRINSCH-MQW) LD structures with 2, 4, 8 and 16 GaAs quantum wells (QWs) were used to evaluate quantitatively the effect of the number of QWs in the performance of LDs. Threshold current density values of 358 Ai cm(2) for 2 QWs, 484 A/cm(2) for 4 QWs, 685 A/cm(2) for 8 QWs and 1435 A/cm(2) for 16 QWs were measured. PDs were: fabricated by five GRINSCH-MQW structures with 2 32 QWs and exhibited responsivity of 0.020 A/W for 2 QWs, 0.031 A/W for 4 QWs, 0.069 A/W for 8 QWs, 0.181 A/W for 16 QWs and 0.350 AW for 32 QWs.