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

Electronic energy calculations of Cu-doped BaSi2, an expected solar-energy material, have been performed by a density-functional theory assuming several possible insertion sites of Cu into the BaSi2 lattice. The 4c sites, which are surrounded by three Si atoms, one of which is at a peak of one Si-tetrahedron and other two of which are composing an edge of the other Si-tetrahedron, will be the most favorably inserted by Cu atoms. This insertion reaction is energetically more favorable than the substitution reactions of Ba or Si by Cu. Insertion of Cu into BaSi2 will cause the n-type behavior of semiconducting BaSi2. This prediction is consistent with the observed facts.