Diffusion, activation, and recrystallization of boron implanted in preamorphized and crystalline germanium

We have investigated diffusion and activation of boron implanted with 6 keV energy to a maximum concentration of $8.0×1020atoms∕cm3$ in crystalline germanium (⁠$c$-germanium) and preamorphized germanium, employing rapid thermal annealing in the range of 400–600 °C. As-implanted boron profiles in preamorphized germanium are shallower than the ones in $c$-germanium due to channeling suppression. While boron diffusion is not observed either in $c$-germanium or during the germanium regrowth from amorphous state, the boron activation level achieved from the two starting phases is significantly different. A boron activation level of $2.4×1020atoms∕cm3$ has been found in regrown germanium, while a level of only $1.2×1019atoms∕cm3$ is observed in $c$-germanium. Remarkably, there is no evidence of any residual extended defectivity at the original crystalline/amorphous interface, when preamorphization is performed.