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" High-frequency electrical properties of polycrystalline diamond "
M. M. Bataineh
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1112932
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| Doc. No
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TLpq304357193
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| Main Entry
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M. M. Bataineh
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| Title & Author
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High-frequency electrical properties of polycrystalline diamond\ M. M. Bataineh
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| College
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Michigan State University
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| Date
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1997
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| student score
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1997
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| Degree
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Ph.D.
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| Page No
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156
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| Abstract
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Diamond is a material of great interest for various high frequency electronic applications stemming from its constellation of material properties, including large energy gap, high breakdown field, and high free carrier saturation velocity, among others. However, there are several outstanding questions regarding the frequency dependent electrical properties of diamond. For example, it is not clear whether observed frequency dependencies are mainly due to inter-grain or intra-grain effects. Also it is not clear whether grain boundary effects on frequency dependent conductivity is mainly due to hopping or to potential barrier capacitive effects. This dissertation addresses these basic questions by analyzing results over a broad frequency range so as to separate the roles of these phenomena. The impedance spectroscopy method is used to study electrical conduction in diamond over a frequency range from dc to 1GHz. Both thick, free-standing films (200 to 400 mum thickness) and thin films on silicon (3 to 6 mum thickness) are investigated. Experimental results fit well to an electrical model which includes both a hopping conduction path and a path representing cross-grain-boundary conduction. For finer-grain, thin film samples, the data indicates that hopping plays the larger role. However, this was not the case for the larger-grain, thick film samples for which the cross-grain-boundary path dominated the frequency dependent admittance between 1 MHz and 100 MHz. Correlations are investigated between the dc and ac electrical properties of diamond, and the input and output growth parameters. The study of the relationship to deposition parameters implies that the hydrogen flow rate is the single most dominant parameter in determining the dc as-grown electrical resistivity. As for the ac properties, the effects of annealing and temperature on electrical conductivity and on the ac circuit model parameters suggest that the incorporation of hydrogen in the diamond films takes place at the grain boundaries, and not within the crystallites themselves. In conclusion, the study shows that the frequency dependent electrical properties of polycrystalline diamond, beyond those expected as a result of the samples geometric capacitance, are principally associated with grain boundaries. Both hopping and cross-grain boundary conduction paths play important roles in the total conduction process of the diamond films.
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| Subject
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Applied sciences
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chemical vapor deposition
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Electrical engineering
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