Polarization driven covalently-bonded octahedral-twinning and backbone-peripheral-helical nanoarchitectures

We report the novel superstructural chiral polar-surface induced backbone-peripheral-helical (BPH) hierarchical architecture of zincblende SiC made possible by precise helical epitaxy. We show by direct image that this architecture has the mother-daughter relationship. The center of the BPH consists of periodic octahedral modular units with chiral sidewalls. By forming Si-C covalent bonds at the sidewalls, a daughter SiC wire spontaneously vine-grows in a peripherally helical way on the mother wire. All of the information of the mother wire, including twinning, polarity and even stacking fault, are completely copied and inherited by the daughter wire one-by-one at the atomic level. Our findings thus provide a simple growth method and the necessary atomistic mechanism for novel polar surface driven superstructural twinning and subsequent BPH growth, which should be universal for zincblende semiconductors and even could be true for other noncentral-symmetric compounds.