Energetic evaluation of possible insertion sites of Cu into BaSi2 using first principle calculations

► This paper reports the results of calculation of electronic energies of Cu-doped BaSi2. Possible insertion sites into the BaSi2 lattice were explored and it was found that energy change of insertion reaction, Ba8Si16 + Cu → Ba8Si16Cu1…(1), is negative (ca. −3.4 eV) when the sites, which are surrounded by three Si atoms, one of which is in a peak of one Si-tetrahedron and other two of which are composing an edge of the other Si-tetrahedron, is occupied by a Cu atom. On the contrary, energy change of substitution reactions of Ba8Si16 + Cu → Ba7Cu1Si16 + Ba…(2) or, Ba8Si16 + Cu1 → Ba8Si15Cu1 + Si…(3) are positive. Thus, probable reaction of Cu-doping is the insertion. Inserted Cu will work as an electron-donor, which is consistent to the observed n-type behaviors of Cu-doped BaSi2.