P implantation doping of Ge: Diffusion, activation, and recrystallization

We have studied doping profiles, activation levels, and defect annealing of P introduced in Ge by ion implantation at different doses and energy, and annealed under various conditions by rapid thermal annealing. Common to all implant energies, ion-implanted P in Ge exhibits a “box profile” at high implant doses, when a sufficiently high thermal budget is applied—similarly to the concentration-dependent diffusion of P introduced in Ge from a high-concentration solid source. Upon proper annealing conditions, the active P concentration is limited to (5–6)×1019at.∕cm3, implying a 50% activation level of the total retained atoms for high-dose implants and 100% for the low-dose implants. A low thermal budget is sufficient to fully regrow the amorphous layer formed by high-dose P implantations, without evidence of residual defects in the regrown germanium layer and at the end of range of the P implant.