First-principles study on the surface properties of single-crystalline InP tetrapods

Ⅲ-Ⅴ colloidal nanocrystals containing non-toxic elements and covalent bonding unlike Ⅱ-Ⅵ or Ⅳ-Ⅵ QDs have greatly attracted attention as the candidates for optoelectronic devices such as photovoltaics and displays. Since the most atoms in the nano-sized crystal are exposed to the outer, configuration and composition of surface is key factor to determine the structure and physical properties of nanocrystals. Here, we performed the first-principles calculation to explain the formation mechanism of late intermediate, tetrapod, and reaction product, tetrahedron single crystalline InP QDs by evaluating the stabilities of them. The surface formation energies of the tetrapod consisting of {110} and (111):P facets and the tetrahedron covered by (111):In facets indicate that tetrapod is a metastable intermediate and tetrahedron is thermodynamically stable product.