In situ reflectance anisotropy spectroscopy was employed to interpret the surface reaction rate constant (ks) of a Ga precursor on a GaAs(001) surface in metallorganic vapor-phase epitaxy (MOVPE), which was extracted by the analysis of selective-area growth. The activation energy of ks significantly decreased above 625-630°C. Correspondingly, the surface anisotropy spectrum changed around 600°C from that of surface reconstruction containing Ga dimers at lower temperatures to that of c (4×4) -like reconstruction with As dimers at higher temperatures. These observations suggest a step-flow growth mode at higher temperatures and an island growth mode at lower temperatures.
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