In situ thermal evolution of B-B pairs in crystalline Si: a spectroscopic high resolution x-ray diffraction study

The lattice strain induced by the thermal evolution of B-B pairs formed in a Si1-xBx/Si layer as a consequence of He irradiation has been studied in situ in an N-2 atmosphere, by using a high resolution x-ray diffractometer equipped with a hot stage sample holder. The collection of repeated rocking curves during a linear temperature (T) ramp allowed monitoring of the effects of the B-B pair thermal evolution on the epilayer lattice parameter a (and equally its strain) during the whole of the annealing from room T up to their complete dissolution (883 degrees C). By analysing the evolution of a(T) we extracted detailed information about the kinetics of B-B pair evolution. This allowed us to determine an experimental description of the B-B pair dissolution path in good agreement with recent ab initio calculations.