Effect of oxygen incorporation in the Mg2Si lattice on its conductivity type – A possible reason of the p-type conductivity of postannealed Mg2Si thin film

• Possible reasons for the p-type conductivity of post-annealed Mg2Si thin film were examined.
• Oxygen-intercalation into the Mg2Si lattice is energetically more favorable than substitutional reactions.
• Oxygen-intercalation would cause p-type conductivity because oxygen in Mg2Si will work as a recipient of electrons.

We examined the possible reasons for the p-type conductivity of undoped, post-annealed Mg2Si thin film prepared by sputtering deposition process. Since it would not be able to explain the results by taking only recovery of the lattice defects into consideration, we paid attention to the possible oxygen(O)-incorporation through substitutional reaction of Mg and Si by O and O-intercalation into the 4b site of Mg2Si lattice. Energetic evaluations by using 1st principle calculations showed that O- intercalation is the most probable reaction and this would cause p-type conductivity because oxygen in Mg2Si will work as a recipient of electrons.