Density functional theory (DFT) study of Zn, O2 and O adsorption on polar ZnO(0001) and ZnO (0001) surfaces

• Zn atom is adsorbed at polar ZnO surfaces with adsorption energies 0.34 eV for Zn and 3.37 eV for O face.
• O atom is adsorbed at polar ZnO surfaces with adsorption energies 5.47 eV for Zn and 2.47 eV for O face.
• O2 molecule is adsorbed at Zn face with the energy 2.45 eV.
• O2 molecule is not adsorbed at O face.

Ab initio DFT simulations of Zn and O atoms and O2 molecules adsorption on polar 2H–ZnO(0001) and 2H–ZnO(0001) surfaces elucidated the principal processes, important for growth of zinc oxide from the vapour. It was shown that a zinc atom is adsorbed at both ZnO surfaces without any energy barrier but with ultimately different adsorption energies: 0.34 eV for the metallic and 3.37 for the non-metallic surface. Oxygen atoms are attached very strongly at both polar surfaces, with energies equal to 5.47 eV and 2.47 eV. The difference between both polar surfaces is the largest for adsorption of molecular oxygen, the O2 molecule is adsorbed on the Zn-face with the energy 2.45 eV while it is not adsorbed at the oxygen face of zinc oxide.