Defects, structure, and chemistry of InP-GaAs interfaces obtained by wafer bonding

We have examined the crystallographic structure of GaAs/InP interfaces obtained by wafer fusion following different procedures. Plan-view and cross-sectional transmission electron microscopy reveal that the interface is not only composed of a regular array of two sets of edge dislocations and is more complex than generally supposed. If a twist is created due to misalignment of the two substrates, the dislocations are not edge dislocations but also have a screw component. Dislocations for which the Burgers vectors have a component normal to the interface are also present. Those dislocations probably result from steps and some of them accommodate the tilt between the two substrates. Inclusions and voids as well as a low number of volume dislocations are present in all the samples. The observed volume dislocation density near the interface lies in the 10(5)-10(7) cm(-2) range and these volume dislocations may be associated with thermal mismatch. The origin of all these defects is discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)08306-7].