Preparation and analysis of thin film electroluminescent devices

Markku Ylilammi

    Research output: ThesisDissertationCollection of Articles


    Alternating current thin film electroluminescent (ACTFEL) displays are manufactured by thin film technology. The development of these devices has followed the advances made in the deposition and analysis of the phosphor, insulator, and conducting layers. In this work Atomic Layer Deposition (ALD) has been applied in the deposition of phosphor and dielectric films (including fluorides and composite insulators) and new means for their characterization are devised. In addition, the mechanism of the ALD method in general is discussed. Progress in understanding ACTFEL devices has been achieved by physical, electrical, and optical modeling. In this thesis these topics are taken further and the development of a simple scheme to combine the theories into a complete model for the picture element is attempted. This approach provides tools for the preparation of new optimized structures in the area of multicolor displays in particular. Instrumental in this progress is the application of powerful analysis methods that give information about the structure and processes in the thin film stack. In this work the traditional measurements of electrical and optical properties have been extended by fitting the measured continuous data to theoretical models. This allows the evaluation of a number of internal parameters which previously were only indirectly obtained. A method is devised for condensing information about the highly nonlinear breakdown in the phosphor layer into a few characteristic parameters. For fast film thickness determination in multilayer stacks, optical spectroscopy is a unique method. These measurements are used to deduce the visual and electrical properties of an ACTFEL display.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Helsinki University of Technology
    Print ISBNs951-666-493-8
    Publication statusPublished - 1996
    MoE publication typeG5 Doctoral dissertation (article)


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