Details

Autor(en) / Beteiligte

• Mun Wong, Kin
• Alay-e-Abbas, S. M.
• Shaukat, A.
• Fang, Yaoguo
• Lei, Yong

Titel

First-principles investigation of the size-dependent structural stability and electronic properties of O-vacancies at the ZnO polar and non-polar surfaces

Ist Teil von

• Journal of applied physics, 2013-01, Vol.113 (1)

Erscheinungsjahr

2013

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In this paper, all electron full-potential linearized augmented plane wave plus local orbitals method has been used to investigate the structural and electronic properties of polar (0001) and non-polar (101¯0) surfaces of ZnO in terms of the defect formation energy (DFE), charge density, and electronic band structure with the supercell-slab (SS) models. Our calculations support the size-dependent structural phase transformation of wurzite lattice to graphite-like structure which is a result of the termination of hexagonal ZnO at the (0001) basal plane, when the stacking of ZnO primitive cell along the hexagonal principle c-axis is less than 16 atomic layers of Zn and O atoms. This structural phase transformation has been studied in terms of Coulomb energy, nature of the bond, energy due to macroscopic electric field in the [0001] direction, and the surface to volume ratio for the smaller SS. We show that the size-dependent phase transformation is completely absent for surfaces with a non-basal plane termination, and the resulting structure is less stable. Similarly, elimination of this size-dependent graphite-like structural phase transformation also occurs on the creation of O-vacancy which is investigated in terms of Coulomb attraction at the surface. Furthermore, the DFE at the (101¯0)/(1¯010) and (0001)/(0001¯) surfaces is correlated with the slab-like structures elongation in the hexagonal a- and c-axis. Electronic structure of the neutral O-vacancy at the (0001)/(0001¯) surfaces has been calculated and the effect of charge transfer between the two sides of the polar surfaces (0001)/(0001¯) on the mixing of conduction band through the 4s orbitals of the surface Zn atoms is elaborated. An insulating band structure profile for the non-polar (101¯0)/(1¯010) surfaces and for the smaller polar (0001)/(0001¯) SS without O-vacancy is also discussed. The results in this paper will be useful for the tuning of the structural and electronic properties of the (0001) and (101¯0) ZnO nanosheets by varying their size.