Dose rate effects on the dynamic annealing mechanism in P+-implanted silicon

In order to clarify the influence of dose rate on the dynamic recrystallization mechanism in Si implanted at high dose rate, experiments are performed by implanting 100 keV P+ ions at current densities of 60, 120, 240, and 500 μA/cm2. TEM and RBS analyses show that the amount of crystalline material which remains on the surface of the specimen after the early stage of bombardment as a result of incomplete amorphization, decreases with increasing ion flux. As a consequence, the subsequent recrystallization from the surface, which was substantial in samples implanted at a flux density of 60 μA/cm2, is less important for irradiation at 120 μA/cm2 and practically absent for irradiations at 240 and 500 μA/cm2. Moreover, it is found that, in the temperature range investigated, the amount of recrystallization which takes place from the deep amorphous-crystalline interface is not appreciably dependent on dose rate, being simply proportional to the implanted dose. These results clarify the influence of the dose rate on the mechanism of amorphization during the early stage of implantation. (author)