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postgraduate thesis: Atomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles

TitleAtomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles
Authors
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Yang, Y. [楊暘]. (2012). Atomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4819951
AbstractZinc oxide surfaces have been of considerable interest because of their favorable properties, such as high electron mobility, good transparency, large electronic breakdown field and wide bandgap. Knowing the surface structure of ZnO is the key to better understand the above phenomena and to further develop its applications. In this thesis, the Patterson Function was evaluated by inversion of LEED I-V spectra at multiple incident angles to determine the surface structure of the ZnO(0001) polar surface. The sample was prepared by degassing and then 15 cycles of argon sputtering and annealing. The experimental LEED I-V spectra from multiple incident angles were taken from the sample. After processing the data by a macro program in OPTIMAS and a Matlab program, a clean Patterson Function map showing the inter-atomic pair distances was obtained. It was then compared with the simulated Patterson Function map of the proposed 1×1 bare surface model. As a result, the spots positions in the simulated Patterson Function map matched well with that of the experimental Patterson Function map. On the other hand, the LEED I-V curve fitting work was done by the surface science group of City University of Hong Kong. Six models were proposed by them and normal incidence theoretical LEED I-V spectra were calculated to fit with the experimental LEED I-V curves provided by us. Among the six models 2×2 Zn point defect model was fitted to be the best model with the R-factor 0.244. We also compared the multiple scattering simulated Patterson Function map of 2×2 Zn point defect model with the experimental one to verify the validity of the model. As a result, the model fit the experimental data. So we conclude that in general 1×1 model support the order part, and 2×2 top layer Zn defect model best fits the random missing part.
DegreeMaster of Philosophy
SubjectZinc oxide - Surfaces.
Low energy electron diffraction.
Dept/ProgramPhysics

 

DC FieldValueLanguage
dc.contributor.authorYang, Yang-
dc.contributor.author楊暘-
dc.date.issued2012-
dc.identifier.citationYang, Y. [楊暘]. (2012). Atomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4819951-
dc.description.abstractZinc oxide surfaces have been of considerable interest because of their favorable properties, such as high electron mobility, good transparency, large electronic breakdown field and wide bandgap. Knowing the surface structure of ZnO is the key to better understand the above phenomena and to further develop its applications. In this thesis, the Patterson Function was evaluated by inversion of LEED I-V spectra at multiple incident angles to determine the surface structure of the ZnO(0001) polar surface. The sample was prepared by degassing and then 15 cycles of argon sputtering and annealing. The experimental LEED I-V spectra from multiple incident angles were taken from the sample. After processing the data by a macro program in OPTIMAS and a Matlab program, a clean Patterson Function map showing the inter-atomic pair distances was obtained. It was then compared with the simulated Patterson Function map of the proposed 1×1 bare surface model. As a result, the spots positions in the simulated Patterson Function map matched well with that of the experimental Patterson Function map. On the other hand, the LEED I-V curve fitting work was done by the surface science group of City University of Hong Kong. Six models were proposed by them and normal incidence theoretical LEED I-V spectra were calculated to fit with the experimental LEED I-V curves provided by us. Among the six models 2×2 Zn point defect model was fitted to be the best model with the R-factor 0.244. We also compared the multiple scattering simulated Patterson Function map of 2×2 Zn point defect model with the experimental one to verify the validity of the model. As a result, the model fit the experimental data. So we conclude that in general 1×1 model support the order part, and 2×2 top layer Zn defect model best fits the random missing part.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.source.urihttp://hub.hku.hk/bib/B48199515-
dc.subject.lcshZinc oxide - Surfaces.-
dc.subject.lcshLow energy electron diffraction.-
dc.titleAtomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles-
dc.typePG_Thesis-
dc.identifier.hkulb4819951-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b4819951-
dc.date.hkucongregation2012-

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