First-principles calculation of impurity doping into Mg2Ge

The formation energy, structural relaxation, and Mulliken charge of impurities in Mg2Ge are systematically investigated using first-principles calculations based on the density functional theory. Among the elements in groups Ia, IIIa, Ib, IIIb, and Vb, Sc, Y, La, P, N, As, Sb, and Bi are suggested as n-type dopants. whereas Li, Na, K, Rb, and B are suggested as p-type dopants. For Al, In, Ga, Ag, and Cu, the conduction type depends on the atomic chemical potentials of Mg and Ge The formation energies of P, As, Sb, Bi, and Au in the Ge-site substitution as well as those of Li, Sc, and Y in the Mg-site substitution are negative at Mg- and/or Ge-rich limits, suggesting that these impurities have good solubility. The carrier type of impurity-doped Mg2Ce will be influenced by the types of dopants and the substitution site. The strong similarity between the formation energies of the groups Ib, IIIb, and Vb impurities in Mg2Ge and Mg2Si is observed. (C) 2009 Elsevier B.V. All rights reserved.