Electronic Structure and Band Gap Engineering of ZnO-based Semiconductor Alloy Films

P-L Liu, P-T Shao
National Chung Hsing University, TW

Keywords: first-principles calculations, ZnO, band gap

Summary:

We conduct first-principles total-energy density functional calculations to study the band structures and atomic structures in ZnO and Zn0.5M0.5O alloys using the planewave projector augmented-wave (PAW) method with the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. We find 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 behavior interpreted with the unique spatial distribution pattern between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). The cations of Be, Mg, and Cd can greatly distort the lattice but do not modify the intrinsic nature of the HOMO-LUMO isosurfaces in ZnO indicating the direct-gap behavior. These finding could lead to the development of ZnO-based semiconductors due to a wide range of operating wavelengths in the blue, green and ultraviolet (UV) lighting.