Energetics of intrinsic defects and their complexes in ZnO investigated by density functional calculations

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.83.045206· OSTI ID:21538067

Vidya, R; Ravindran, P; Fjellvaag, H ^[1]; Svensson, B G; Monakhov, E ^[2]; Ganchenkova, M; Nieminen, R M ^[3]

---

1. Center for Materials Science and Nanotechnology and Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315 Oslo (Norway)
2. Center for Materials Science and Nanotechnology and Department of Physics, Physical Electronics, University of Oslo, Box 1048 Blindern, N-0316 Oslo (Norway)
3. Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, F-02015 HUT (Finland)

Formation energies of various intrinsic defects and defect complexes in ZnO have been calculated using a density-functional-theory-based pseudopotential all-electron method. The various defects considered are oxygen vacancy (V{sub O}), zinc vacancy (V{sub Zn}), oxygen at an interstitial site (O{sub i}), Zn at an interstitial site (Zn{sub i}), Zn at V{sub O} (Zn{sub O}), O at V{sub Zn}(O{sub Zn}), and an antisite pair (combination of the preceding two defects). In addition, defect complexes like (V{sub O}+Zn{sub i}) and Zn-vacancy clusters are studied. The Schokkty pair (V{sub O}+V{sub Zn}) and Frenkel pairs [(V{sub O}+O{sub i}) and (V{sub Zn}+Zn{sub i})] are considered theoretically for the first time. Upon comparing the formation energies of these defects, we find that V{sub O} would be the dominant intrinsic defect under both Zn-rich and O-rich conditions and it is a deep double donor. Both Zn{sub O} and Zn{sub i} are found to be shallow donors. The low formation energy of donor-type intrinsic defects could lead to difficulty in achieving p-type conductivity in ZnO. Defect complexes have charge transitions deep inside the band gap. The red, yellow, and green photoluminescence peaks of undoped samples can be assigned to some of the defect complexes considered. It is believed that the red luminescence originates from an electronic transition in V{sub O}, but we find that it can originate from the antisite Zn{sub O} defect. Charge density and electron-localization function analyses have been used to understand the effect of these defects on the ZnO lattice. The electronic structure of ZnO with intrinsic defects has been studied using density-of-states and electronic band structure plots. The acceptor levels introduced by V{sub Zn} are relatively localized, making it difficult to achieve p-type conductivity with sufficient hole mobility.

• OSTI ID: 21538067
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 4; Other Information: DOI: 10.1103/PhysRevB.83.045206; (c) 2011 American Institute of Physics; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
CHARGE DENSITY
COMPLEXES
COMPUTERIZED SIMULATION
CRYSTAL DEFECTS
DENSITY
DENSITY FUNCTIONAL METHOD
ELECTRONIC STRUCTURE
ELECTRONS
FORMATION HEAT
HOLE MOBILITY
INTERSTITIALS
PHOTOLUMINESCENCE
VACANCIES
ZINC
ZINC OXIDES
CALCULATION METHODS
CHALCOGENIDES
CRYSTAL STRUCTURE
ELEMENTARY PARTICLES
ELEMENTS
EMISSION
ENTHALPY
FERMIONS
LEPTONS
LUMINESCENCE
METALS
MOBILITY
OXIDES
OXYGEN COMPOUNDS
PHOTON EMISSION
PHYSICAL PROPERTIES
POINT DEFECTS
REACTION HEAT
SIMULATION
THERMODYNAMIC PROPERTIES
VARIATIONAL METHODS
ZINC COMPOUNDS