Interface of directly bonded GaAs and InP

The structure and composition of the interface of directly bonded GaAs and InP (001) wafers has been studied with various techniques in electron micro scopy. For each interface three different dislocation networks have been id entified and analyzed. They have been confirmed to accommodate the lattice mismatch, the tilt misfit between the two wafers, and the thermal misfit, r espectively. Interdiffusion of both group-III and group-V elements takes pl ace. Indium diffusion is enhanced by the Zn dopant and its segregation. The "cavities" at the interface, reported in the literature, have been found t o be associated with indium depletion. In the case of inadequate surface pr eparation prior to bonding an amorphous layer of native oxide(s) forms at t he interface. The actual bonding temperature T-b at which the atomic bonds construct locally across the two surfaces of the wafers is lower than the a nnealing temperature employed in the present experiments. It is therefore s uggested that a better interface may be achieved by improving the preparati on of the surfaces of the wafers with appropriate chemicals and by bonding the wafers at a lower temperature. (C) 2001 American Institute of Physics.