Abstract
Using the spot profile analysis, reflection high-energy electron diffraction (RHEED) can be advantageously applied for defect structure evaluation. Two types of GaAs(001) surfaces has been studied that are prepared by molecular beam epitaxy (MOE) under As-rich growth conditions, surfaces as they develop during growth on slightly misoriented GaAs(001) substrates, and those observed after growth on substrates without intended misorientation. RHEED patterns for intensity profile measurements by photodensitometry were photographically recorded using an in situ system (15 kV) and an ex-situ apparatus (50 kV), respectively. This chapter shows a typical pattern with clearly resolved slashes taken from a misoriented Ge(001) surface. Similar patterns evidencing the development of ordered arrays of steps one monolayer GaAs in height were obtained also for GaAs films grown on misoriented GaAs(001) substrates. For small misorientations and less well-ordered step arrays, however, the clear diffraction features are diminishing. The profiles for the singular GaAs(001) surface are also discussed, which show a sharp central spike and a broadened part. Their relative contributions change periodically with K⊥. This can be understood within the framework of a model of irregular step arrays with only a few levels included in step formation.
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