Electronic structure and band gap engineering of ZnO-based semiconductor alloy films

We have conducted first-principles total-energy density functional calculations to study the atomic structures, band structures and electronic structures of Zn1-xMxO (M=Be, Mg, Cd, Ag, Cu) semiconductor alloys. The Heyd-Scuseria-Ernzerhof hybrid functional has been performed to yield lattice constants and band gaps of Zn1-xMxO semiconductor in much better agreement with experimental data than with the standard local exchange correlation functional. We found that the strong coupling between O 2p and Cu 3d or Ag 4d bands plays a key role in narrowing of band gaps and leading to the half-metallic behaviour interpreted with the unique spatial distribution pattern between the highest occupied molecular orbital and the lowest unoccupied molecular orbital.