HVPE growth of Si crystal with topological chiral morphology

Topological chiral occurs when a crystal has an asymmetric structure that does not overlap with the mirror image. In this study, Si crystals with a topological chiral morphology were grown via mixed-source hydride vapor phase epitaxy (HVPE). AlN-based nanowires consisting of Al and Ga metal chlorides were changed to Si crystals, resulting in the formation of topological chiral Si crystals at the inflection point. The Si crystals grown from the AlN-based nanowires were single crystals exhibiting chirality based on an arbitrary point. In this study, we used 2H-Si lattice constants to predict the lattice structure at the inflection point of topological chiral Si crystals. As a result, a typical 2H-Si structure can be expected from the crystal structure at the top and bottom, and a topological chiral Si crystal with an inflection point rotated by 30° was confirmed. A high-resolution optical three-dimensional surface analyzer, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, high-resolution X-ray diffraction, and Raman spectroscopy were used to analyze the topological chiral Si crystals. The results indicated that topological chiral Si crystals can be used as a new quantum material that can be applied to high-power spintronic devices.