Results on the specular beam intensity behavior in reflection high‐energy electron diffraciton during molecular beam epitaxial growth of Al0.3Ga0.7As on GaAs(100) are reported. The behavior of steady‐state intensity as a function of substrate temperature exhibits irreversible character. The results indicate that the Al reactivity with As and residual impurities is the dominant factor controlling the surface morphology and hence the nature of inverted interfaces. A critical need for choosing optimal growth conditions prior to initiation of Al0.3Ga0.7As growth thus emerges.