2H–Si/Ge for Group-IV Photonics: on the Origin of Extended Defects in Core–Shell Nanowires

The nucleation mechanism of ubiquitous basal stacking faults observed in hexagonal Si/Ge nanowires is still an enigma. These defects may hinder the exploitation of hexagonal Si/Ge for nano-optoelectronics and quantum technologies. In this work, the formation of the I3 basal stacking faults is investigated at the atomistic level, and results are compared to the experimental findings. We propose that these extended defects are caused by dislocation lines elongated in ⟨112̅0⟩ directions, which in turn arise from glide terminations of the step edges when two growing fronts run into each other.