Atomic structure of the interface of GaAs on vicinal Si(001)

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Abstract
The interface structure of GaAs on Si(001) grown by molecular beam epitaxy was examined by high-resolution transmission electron microscopy. The interface was characterized regarding the arrangement of atoms, the chemical abruptness, the structure and density of misfit dislocations, the position of misfit dislocations with respect to the chemical interface and the position and height of substrate steps. An abrupt chemical transition within a bilayer was found between GaAs and Si. The lattice mismatch is relieved by Lomer and 60[ddot] misfit dislocations. 90[ddot] partial and 30[ddot] partial dislocations terminating stacking faults and microtwins also contribute to the mismatch relaxation. Different delocalizations of the Lomer dislocation core along the interface were observed indicating that Lomer dislocations are generated by the agglomeration of two 60[ddot] dislocations that climb along the interface.