Investigation on direct bonding of III–V semiconductor wafers with lattice mismatch and orientation mismatch

The direct bonding of various III–V wafers with mismatches in terms of lattice constants and surface orientations was systematically investigated for an In–Ga–As–P system. Many wafer combinations were bonded with sufficient mechanical strength, despite those mismatches. The bonding interface of (001) GaP and (110) InP was observed by transmission electron microscopy and found to be bonded at the atomic level without any defects occurring. The electrical property of the bonding interface was examined for several bonded structures of GaAs and InP. The results support a novel concept ‘‘free-orientation integration,’’ which should be achieved by direct bonding.