ATOM-REARRANGEMENT IN GE LAYER GROWN ON SI SUBSTRATE DURING ANNEAL OBSERVED IN REAL-TIME BY COAXIAL IMPACT COLLISION ION-SCATTERING SPECTROSCOPY

The atom-rearrangement in thin Ge layers grown on Si(001) substrates during post-growth anneal has been studied using coaxial impact collision ion scattering spectroscopy (CAICISS). CAICISS measurements were carried out in real time during the anneal. A Ge layer was grown at 130 degrees C by molecular beam epitaxy, and after growth the sample temperature was raised to 600 degrees C at a rate of 1 degrees C/s. The intensity of the back-scattered ion beam with incidence along the [01 ($) over bar 1] direction was measured during the anneal. A gradual decrease in the scattering intensity was observed while the temperature was raised from 300 to 520 degrees C. The decrease in the scattering intensity observed here can be understood in terms of a reduction in the number of interstitial atoms due to atom-rearrangement along the [01 ($) over bar 1] direction. Plan-view transmission electron microscope (TEM) images showed clear moire fringes for the sample after anneal, while such moire fringes were not observed for an as-grown sample. The result of a TEM observation also shows atom-rearrangement in the Ge layer due to the anneal, which is in good agreement with the results of CAICISS measurements.