The Epitaxy of 2D materials growth

A general theoretical framework for the epitaxial growth of a 2D material on an arbitrary substrate was proposed. Our extensive density functional theory (DFT) calculations show that the propagating edge of a 2D material tends to align along a high symmetry direction of the substrate and, as a conclusion, the interplay between the symmetries of the 2D material and the substrate plays a critical role in the epitaxial growth of the 2D material. Based on our results, we have outlined that unidirectional align-ment of 2D material islands on a substrate can be realized only if the symmetry group of the substrate is a subgroup of that of the 2D material. Our predictions are in perfect agreement with most experi-mental observations on 2D materials’ growth on various substrates known up to now. We believe that this general guideline will lead to the large-scale synthesis of wafer-scale single crystals of various 2D materials in the near future.

Colloidal trains

Colloidal trains consisting of colloidal doublet locomotives and single colloidal carriages self assemble above a magnetic square pattern and are driven by an external magnetic field processing around a high symmetry direction.

Structure of Kcn Monolayer Films Vapor-Deposited onto Cleaved KBr(001) by Helium Atom Diffraction

Angular distribution measurements of the helium atom scattering intensity from monolayer films of KCN/KBr(001) for several azimuths over a temperature range of approximately 40–200 K reveal that above ˜95 K the KCN monolayer forms a (1×1) overlayer structure with respect to the KBr substrate. (The lattice spacing of bulk KCN in the rocksalt-structure phase differs from that of KBr by only ˜ 1%.) Below this temperature the overlayer appears to be (2×1), and “missing” diffraction spots in the <110> high symmetry direction suggest the existence of a glide plane. The inferred structure for this low temperature phase consists of K+ ions fixed in their rocksaltstructure positions relative to the substrate and the CN− ions oriented so that their dipoles are aligned antiferroelectrically within the new unit cell.