UNUSUAL STRAIN RELAXATION IN SIGE SI HETEROSTRUCTURES/

Si1-xGex films (x=0.22) epitaxially grown by ion beam-sputter depositi on on (001) Si substrates were subjected to rapid and conventional the rmal annealings at different temperatures. Strain measurements carried out by means of high-resolution x-ray diffraction exhibited strongly nonmonotonous strain dependencies on the annealing time. We observed s hort-time and long-time relaxation modes with activation energies of 4 .6 and 1.3 eV respectively, and unexpectedly, an additional mode of st rain recovery at intermediate time durations with an activation energy of 1.6 eV. This behavior was attributed to processes that involve {11 3} two-dimensional defects, i.e., agglomerates of interstitials, which were identified by means of transmission electron microscopy. (C) 199 7 American Institute of Physics.