The influence of growth temperature on the period of RHEED oscillations during MBE of Si and Ge on Si(111) surface

The thickness of a film growing during one oscillation period at MBE of sil icon and germanium on a slightly misoriented Si(111) surface was measured a s a function of temperature. The temperature elevation was found to result in either an increase or decrease in the oscillation period. That was accou nted for by the occurrence of various barriers for incorporation of adatoms at the upper terrace into differently directed steps. The activation energ ies of nucleation of two-dimensional islands were determined. In the case o f a decrease in the oscillation period the activation energy was 1.45 +/- 0 .1 eV and 1.1 +/- 0.1 eV for epitaxy of silicon and germanium, respectively . In the case of a increase in the oscillation period the activation energy was 0.91 +/- 0.1 eV and 0.49 +/- 0.1 eV for epitaxy of silicon and germani um, respectively. (C) 1998 Elsevier Science S.A. All rights reserved.