Plasma immersion ion implantation doping of thin a-Si:H layers is proposed as a new and easy-to-process solution for the fabrication of interdigitated back contacted a-Si/c-Si heterojunction solar cells (SHJ). This study is focused on boron implantation (at low acceleration voltages in the range of 500-1500 V) in a-Si:H layers on a c-Si substrate, to create the strongly doped emitter while maintaining very high c-Si surface passivation, required for high efficiency SHJ solar cells. The influence of implantation parameters and post-annealing temperature on the a-Si:H layer conductivity and passivation quality are assessed. The doped layers conductivity is also investigated by direct and indirect electrical characterization of the density of states in a-Si:H after ion implantation, and the post-implantation annealing. Eventually, an interesting passivation/doping trade-off is obtained after annealing at 300 C of samples implanted at 1000 V with implied open circuit voltage values of 710 (AE5) mV and conductivity values of the doped a-Si:H layer of 3.0 (AE1.0) Â 10 À5 V À1 cm À1 , which demonstrates that such approach is promising for processing IBC-SHJ cells. Introduction: The interdigitated back contact amorphous/ crystalline silicon (a-Si:H/c-Si) heterojunction solar cell (IBC-SHJ) is one of the most promising architectures. Indeed, the standard SHJ cell architecture already achieved very high efficiencies (25.1% on large area [1]), and the interdigitated back contact architecture allows to suppress shadowing related to the