Skip to content
University of Maryland LibrariesDigital Repository at the University of Maryland
    • Login
    View Item 
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Spectroscopic & Structural Investigation of the Thermal Evolution of Undoped and Phosphorus Doped ZnO and Implications for Unipolar and Bipolar Device Fabrication

    Thumbnail
    View/Open
    umi-umd-3926.pdf (2.568Mb)
    No. of downloads: 2419

    Date
    2006-11-28
    Author
    Pugel, Diane
    Advisor
    Venkatesan, Thirumalai
    Metadata
    Show full item record
    Abstract
    The main objective of this dissertation was to explore the structural, electrical, and optical properties of undoped and extrinsically doped thin film and single crystal ZnO under various growth and processing thermal conditions in the context of understanding intrinsic defect formation and extrinsic dopant incorporation. Undoped (000-1) ZnO thin films were grown by on-axis RF sputter deposition at a range of temperatures and in oxygen-rich and oxygen-deficient atmospheres. For comparison, ZnO single crystals were thermally processed under similar conditions. Samples were examined for temperature-dependent effects on surface and bulk properties for temperature-dependent changes in structure, semiconducting band gap, and Schottky barrier height in order to isolate temperature regions that may support conditions that minimize defect production. Phosphorus-doped (000-1) ZnO thin films were grown and doped ZnO crystals were prepared under the same conditions described above. Phosphorus was selected as a potential p-type dopant due to reduced concerns for outdiffusion of the dopant from the host crystal. Films were grown via sputter deposition. Crystals were prepared via planar (vapor) doping. By investigating undoped ZnO, this work expands current understanding of the fabrication of ZnO-based unipolar devices, such as Schottky diodes. To this end, the structure (surface and bulk), composition, optical, and electrical properties of ZnO single crystals were investigated as a function of annealing temperature and atmosphere. Near-surface diffusion of Zn atoms was found to influence the Schottky barrier height. Annealing conditions that minimize donor defect states, as detected by photoluminescence, were found. By investigating extrinsically doped ZnO, this work sheds light on the feasibility of bipolar device fabrication using ZnO. For film growth, we found a narrow window of deposition temperature and pressure that optimizes crystallinity and transmission in the ultraviolet spectrum for the preparation of p-type doped material. For single crystals, we found optimal conditions for p-type doping ZnO using phosphorus vapor. Results from Hall measurements of these doped single crystals allowed for a revision of the limits defined by previously existing experimental results in the "failure to dope" rule for ZnO.
    URI
    http://hdl.handle.net/1903/4132
    Collections
    • Physics Theses and Dissertations
    • UMD Theses and Dissertations

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility
     

     

    Browse

    All of DRUMCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister
    Pages
    About DRUMAbout Download Statistics

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility