We summarize here a systematic investigation of the structural and electronic properties of III-V/IV semiconductor heterojunctions (with IV $EQ Si, Ge, and III-V $EQ GaAs, AlAs) as well as III-V/IV/III-V single and multiple quantum well structures. All structures were fabricated by molecular beam epitaxy and characterized in-situ by reflection high energy electron diffraction and x-ray photoemission spectroscopy, and ex-situ by x-ray diffraction and transmission electron microscopy. We found that relatively abrupt composition profiles and ideal pseudomorphic growth could be achieved through appropriate deposition conditions. Measurements of the band discontinuities indicated that large deviations from the commutativity and transitivity rules of heterojunction band offsets are observed in most of these interfaces. Such deviations demonstrate the dependence of the band discontinuities on the local interface environment and are related, in general, to the establishment of inequivalent local interface environments.
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