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First Principle Study of Co Doped ZnO

Author: QiaoYuLong
Tutor: ChenChunTian
School: Harbin University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: Co doped ZnO first principle electronic structure magnetic properities
CLC: TN304.21
Type: Master's thesis
Year: 2014
Downloads: 19
Quote: 0
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Abstract


ZnO is a Ⅱ-Ⅵ group compound semiconductor materialwith a direct wideband gap of3.37eV, an excitonic binding energy of60meV. ZnO can be widely usedin the ultraviolet, green, blue and other light-emitting devices and optoelectronic,photovoltaic conversion, optical detection, FET, piezoelectric devices and manyother areas. Curie temperature of diluted magnetic semiconductor materials werecalculated by various theoretical calculation, the results show that the wide band gapsemiconductor oxide ZnO, which incorporation of transition metal ions doped in,may be prepared in dilute magnetic semiconductor materials with room-temperatureferromagnetism. Currently, there are a lot of successful experimental cases of thepreparation of ZnO thin films doped with the transition metals such as Fe, Co, Ni,Mn. However, the origin mechanism of these magnetic materials there are still muchcontroversy.In this paper, the density functional theory (DFT) with the plane-wavepseudopotential method and the total energy of the system whether equal as acriterion are used to research the structural relationship of different geometric modelsof Co-doped ZnO, the relationship between the position of Co atoms and the totalenergy is particularly studied. It is found that there is a certain regularity between theCo atom position and the total energy. This result can be used to simplify simulationmodel number, and a specific design simulation experiment is done to verify ittheoretically. The Co-doped ZnO models, Co doped ZnO with oxygen vacancydefects included models and C、Co co-doped ZnO models are study, on the totalenergy, and the total energy, electronic structure and magnetic properties of themodels are analysed systematically. The different Co impurity concentration impact onthe electronic structure and magnetic of ZnO is researched from the perspective of thedoping concentration. The origin mechanism of magnetic properties of pureCo-doped ZnO is disscussed and analysed by compare the electronic structure of theCo-doped ZnO models and Co doped ZnO with oxygen vacancy defects includedmodels. Through this study, a scientific and reasonable modeling method is firstly givenfor study simulation modeling of periodic crystals. By comparing the electronicstructure of the Co-doped ZnO models and Co doped ZnO with oxygen vacancydefects included models, it is discovered that oxygen vacancies has an importantinfluence on the magnetic properities of Co-doped ZnO material. Theoreticallyanalysing and forecasting that Co and C co-doped ZnO material models have a Curietemperature higher than room temperature.

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Compound semiconductor > Oxide semiconductor
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