Competing influence of damage buildup and lattice vibrations on ion range profiles in Si

Phosphorus depth profiles in Si obtained by 140 keV implantation in the [001] axial channel direction and in a direction 7° off axis are investigated at two different doses (531013 and 5 31015 cm22) for implantation temperatures of 350 °C and room temperature (RT). At low dose and at channeling incidence, the penetration depth of implanted ions is higher at RT than at 350 °C. This behavior is caused by the dechanneling of lattice vibrations. At high dose, the temperature dependence of the shape of the implantation profile is opposite that at low dose, due to enhanced dechanneling by defect accumulation at RT. On the other hand, damage buildup does not occur at elevated temperature. The temperature dependence of the profiles obtained by tilted implantation is much less than for the channeled implants. The P profiles measured can be reproduced very well by atomistic simulations which take into account both lattice vibrations and defect accumulation during ion bombardment