INSITU OBSERVATION OF THE INITIAL GROWTH-STAGES IN GAAS/INAS BY COAXIAL IMPACT COLLISION ION-SCATTERING SPECTROSCOPY - TRANSITION FROM 2-DIMENSIONAL-LIKE TO 3-DIMENSIONAL ISLAND GROWTH

The initial growth stages of the highly lattice-mismatched GaAs/InAs system was studied by coaxial impact collision ion scattering spectroscopy (CAICISS). The GaAs coverage on the InAs substrate during GaAs molecular beam epitaxial growth was monitored in situ by low incident angle CAICISS. The scattering intensity as a function of the deposited amount of GaAs can be divided into three characteristic regions. First, the scattering intensity from In decreases proportionally with the amount of deposited GaAs molecules. However, the intensity decrease stops abruptly before the surface is completely covered with a GaAs layer, and remains constant. Then, the intensity gradually decreases. This result shows that there exist three kinds of growth stages in the process of GaAs deposition on an InAs substrate. The mechanism of the growth mode transition, corresponding to the three kinds of growth stages is discussed from the viewpoint of a strain energy change on the surface.