DFT Study of Structural and Electronic Properties of MgZnO Alloy

Structural and electronic properties of magnesium zinc oxide alloy with different Mg content and different configurations are studied by density functional theory. The energy track of rocksalt and wurtzite phases of MgZnO with different Mg content indicates that below 63% the wurtzite phase is energetically stable and above 63% the rocksalt phase is stable. Distribution of Mg in the MgZnO alloy is important to understand the phase segregation. By analyzing the distribution of Mg in the MgZnO alloy, we find that the energy required for two Mg to stay together is slightly larger than that for two Mg to stay apart, meaning that Mg has the potential to be uniformly distributed in the MgZnO alloy. By comparing with other dopants, we find that Mg introduces smaller lattice distortion. The corresponding electronic properties are studied by analyses of the density of state and the band structure. From the decomposed-projected band structure, we find that the energy level of O 2p orbitals is modulated to lower energy by introducing Mg, indicating that the enlargement of the band gap is partly caused by the subsidence of the valence band. For comparison, Cd modulates O 2p orbitals to a higher energy level, consistent with the presence of a narrow band gap.