Structural studies of Ge–GaAs interfaces

Interface properties of Ge–GaAs grown by molecular beam epitaxy (MBE) have been studied using reflection high energy electron diffraction (RHEED) and high resolution cross-sectional transmission electron microscopy (XTEM). Growth morphology studies using RHEED revealed a smooth surface for the growth of Ge on (100), (110),and (111)GaAs and for that of GaAs on (110)Ge, but indicated a rough surface on an atomic scale for the growth of GaAs on (100) and (111)Ge. The different surface morphologies observed are attributed to the formation of antiphase domains during the growth of GaAs on (100) and (111)Ge. XTEM study of a (100)Ge–GaAs superlattice showed the presence of antiphase boundaries in the GaAs layers but not in the Ge layers. The interface structures of the Ge–GaAs system are discussed based on these RHEED and XTEM results and other information obtained by channeling, Auger, and x-ray measurements.