Emitter saturation current densities, Joe have been investigated with different boron implantation dose and annealing conditions. The higher thermal budgets used here are shown experimentally to improve Joe, implying more complete defect dissolution. Simulations show that significant degradation in Joe can be attributed to the presence of dislocation loops. In addition, in cases where dislocation loops have been annealed, high dose boron implantation still results in stable boron interstitial clusters, which contributes to Joe degradation.