Dynamic process of two-dimensional InAs growth in Stranski–Krastanov mode

In situ investigation of two-dimensional InAs layer, i.e., wetting layer, during the growth in the Stranski–Krastanov mode has been performed by using reflectance-difference (RD) spectroscopy and reflection high-energy electron diffraction (RHEED). RD spectra shows a dramatic change even at 0.1-monolayer (ML) deposition of InAs, which corresponds to a change of the surface reconstruction from the c(4×4) of the As-rich GaAs (0 0 1) to a (1×3) surface reconstruction. With advanced deposition, structures around 2.0 and 2.6 eV gradually change in the sign. The signal inversion at 2.6 eV indicates that the original As dimer along the [1 1 0] becomes dimerized along the [−110]. The 2.0 eV signal, which is related to electronic structures of group-III atoms and As bond, shows a different evolution during the growth. The intensity of the 2.0 eV signal shows the minimum around 1.0-ML deposition. After that, the intensity slightly increases until the start of the dot formation. This results indicates a decrease of In concentration in the wetting layer, i.e., a precursory transport process of In before the dot formation.