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\u2013B pairs formed in a Si1 12xBx/Si layer as a consequence of He irradiation has been studied in situ in an N2 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\u2013B 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 \ub0C). By analysing the evolution of a(T) we extracted detailed information about the kinetics of B\u2013B pair evolution. This allowed us to determine an experimental description of the B\u2013B pair dissolution path in good agreement with recent ab initio calculations