Atomistic behaviour of (n×3)-reconstructed areas of InAs–GaAs(001) surface at the growth condition

We have investigated the spatial evolution of (n×3) surface reconstructed areas during the molecular beam epitaxial growth of InAs–GaAs(001) by using ab initio-based calculation and in situ observation, in order to understand the mechanism of consequent QD nucleation. Statistical analysis of (n×3)-reconstructed morphology reveals that the fraction of (8×3)-reconstructed areas, as well as those of (4×3) and (6×3), appears and decreases in the later stage of the growth. This behaviour is consistent with the result of our ab initio-based calculation incorporating chemical potentials of source materials in the gas phase. In contrast, fragmented (2×3) areas remain throughout the InAs growth as potential QD nucleation sites. •(8×3)-reconstruction on growing InAs–GaAs(001) is predicted by calculation.•The (8×3)-reconstruction is confirmed using in situ STM and statistical analysis.•(4×3), (6×3), (8×3) are increased and gradually replaced by (n×4).•(n×3) areas with n>8 are also observed but decreased more rapidly.•Fragmented (2×3) areas remain during the growth as potential QD nucleation sites.