Intrinsic Point Defects in Zinc Oxide: Modeling of Structural, Electronic, Thermodynamic and Kinetic Properties
The present dissertation deals with the modeling of zinc oxide on the atomic scale employing both quantum mechanical as well as atomistic methods. The first part describes quantum mechanical calculations based on density functional theory of intrinsic point defects in ZnO. To begin with, the geometr...
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| Format: | Others |
| Language: | English en |
| Published: |
2006
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| Online Access: | http://tuprints.ulb.tu-darmstadt.de/726/1/prim.pdf Erhart, Paul <http://tuprints.ulb.tu-darmstadt.de/view/person/Erhart=3APaul=3A=3A.html> : Intrinsic Point Defects in Zinc Oxide: Modeling of Structural, Electronic, Thermodynamic and Kinetic Properties. [Online-Edition] Technische Universität, Darmstadt [Ph.D. Thesis], (2006) |
| Summary: | The present dissertation deals with the modeling of zinc oxide on the atomic scale employing both quantum mechanical as well as atomistic methods. The first part describes quantum mechanical calculations based on density functional theory of intrinsic point defects in ZnO. To begin with, the geometric and electronic structure of vacancies and oxygen interstitials is explored. In equilibrium oxygen interstitials are found to adopt dumbbell and split interstitial configurations in positive and negative charge states, respectively. Semi-empirical self-interaction corrections allow to improve the agreement between the experimental and the calculated band structure significantly; errors due to the limited size of the supercells can be corrected by employing finite-size scaling. The effect of both band structure corrections and finite-size scaling on defect formation enthalpies and transition levels is explored. Finally, transition paths and barriers for the migration of zinc as well as oxygen vacancies and interstitials are determined. The results allow to interpret diffusion experiments and provide a consistent basis for developing models for device simulation. In the second part an interatomic potential for zinc oxide is derived. To this end, the Pontifix computer code is developed which allows to fit analytic bond-order potentials. The code is subsequently employed to obtain interatomic potentials for Zn-O, Zn-Zn, and O-O interactions. To demonstrate the applicability of the potentials, simulations on defect production by ion irradiation are carried out. |
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