We investigate the electrical and structural characteristics after ion implantation of BFx (x=1,2) for silicon solar cells. Compared to non-amorphizing species, e.g. B, amorphizing species, like BF, offer the possibility to lower the thermal budget, which is needed for the curing of implant-induced crystal defects. For implant energies above 30 keV (BF2) we find a strong degradation of the charge carrier lifetime in the volume as well as an increase of the emitter saturation current density J(0) compared to implantation of elemental boron. This behavior can be related to a defective solid phase epitaxy during the recrystallization in the annealing process after implantation. Implantation of BF2 at 10 keV and subsequent annealing at 1050 degrees C for 30 mm results in J(0) values of 41 +/- 3 fA/cm(2) for a planar, Al2O3 passivated 133 Omega/sq emitter. Furthermore, using implantation of BF2 at 20 keV allows lowering the annealing temperature from 1050 degrees C, as commonly used for elemental boron, to 950 degrees C. The latter results in a J(0) of 58 +/- 2 fA/cm(2) for a planar, Al2O3 passivated 141 5-2/sq emitter. (C) 2015 Elsevier B.V. All rights reserved.