We have investigated pulsed excimer and CO2 laser annealing phenomena as a function of laser parameters in boron-implanted silicon, using cross-section transmission electron microscopy. The depth of annealed regions or melting was found to increase linearly with the pulse energy density and inversely with the pulse duration. The threshold for melting and depth of the melted regions as a function of pulse energy density and duration were found to be in good agreement with heat-flow calculations. Pulsed CO2 laser annealing required either high doping or substrate heating to increase free-carrier absorption. The annealing results in both cases were consistent with a first-order phase transformation involving melting.