An InP/InGaAs epitaxial wafer prepared by gas source molecular beam epitaxy was directly bonded with a Si wafer in an ultrahigh vacuum chamber without exposure to the air. The photoluminescence of an InGaAs quantum well layer does not deteriorate even if it is located 100 nm from the bonding interface. In a pin structure fabricated by bonding, carriers injected to the intrinsic region by forward bias reach the interface and recombine through the recombination centers at the interface. ©1996 American Institute of Physics.