Electrical activation of boron in germanium preamorphized silicon after multiple-pulse flash annealing is studied. As the number of pulses increases, enhanced boron deactivation is observed. This deactivation is attributed to boron precipitation into immobile and electrically inactive clusters due to inefficient removal of end-of-range (EOR) defects with the first pulse. Because subsequent pulses are of the same thermal condition as the first, EOR defects remain and additional pulses serve to deactivate the boron atoms further. However, when preceded with spike anneal condition capable of removing the EOR defects, application of additional pulse results in better activation and lower sheet resistance. (C) 2007 The Electrochemical Society.