Energetic and the electronic structural consideration of the 13th Group element (Ga and In) impurity doping to control the conductivity of BaSi2

The energies and the electronic structures of Ga- and In-doped BaSi2 have been calculated using a first-principle pseudopotential method to clarify the reason for observed n-type conduction in Ga-doped BaSi2 and p-type conduction in In-doped BaSi2. Substitution of Si in the BaSi2 lattice by Ga or In is favorable than that of Ba from the energetic point of view. The Fermi level of Ga- or In-doped BaSi2 was predicted to be located close to the top of the valence band in both cases where Ba is substituted by Ga or In and where Si is substituted. This is inconsistent with the simple consideration based on the valence electron concentration. Possible reason of the observed n-type conduction of Ga-doped BaSi2 was proposed.