Delafossite NaYTe2 as a transparent conductive material with bipolar conductivity: A first-principles prediction

Doping asymmetry is a long-standing issue for the progress of wide-bandgap semiconductors, including also several transparent conductors. However, a few compounds exhibit bipolar conductivity, implying a desired band gap in combination with proper energy positions of the band edges according to the empirical doping limit rule. The present first-principles study of delafossite NaYTe2 reveals that the compound is thermodynamic stable with an optical gap energy of ∼3.0 eV and an ionization potential of 6.2 eV, and the electronic structure is thus in the range for realizing bipolar character as a transparent conductive material. In addition, the analysis of the defect properties strengthens this prediction, especially for high free carrier concentration in NaYTe2, obtained by either extrinsic doping or intrinsic defects under suitable growth conditions.