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by Hu Guangda. / "June 2000." / The numerals in the title are subscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 131-141). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

In this thesis, Bi4Ti3O12 thin films are deposited on ITO/glass and Pt/Ti/SiO2/Si substrates using RF magnetron sputtering at room temperature and two kinds of targets with different compositions of Bi4Ti3O12 and Bi4Ti3O12+4wt% Bi2O3, respectively, and then heated by a rapid thermal annealing (RTA) process in an oxygen atmosphere. Three topics are focused in this research, they are: (1) to study the effects of different fabricated conditions and substrates on the physical and electrical characteristics of Bi4Ti3O12; (2) to investigate the influence of bismuth evaporation during thermal process on the characteristics of thin films, and seeking for the methods of bismuth compensation; and (3) applying the Bi4Ti3O12 film as the insulting layer of AC thin film electroluminescence device with the phosphor layer of ZnS:TbOF, and investigating the interaction between the two films. The experimental results indicate that intensities of X-ray diffraction (XRD) peaks of the films are evident when annealing at 650¢J for 15 min or at 700¢J for 10 min using RTA process, and the optimal properties of polycrystalline Bi4Ti3O12 thin films can be obtained at 700¢J for 15 min. No dielectric breakdown phenomenon of the films is detected in the filed of 500 kV/cm, and the leakage current density was lower than 10-6 A/cm2. The dielectric constant can attain to 307, and the loss factor is 0.02 at 1 kHz. The residual polarization and coercive field are 3.7 £gC/cm2 and 80 kV/cm with a sinusoidal wave of 500 Hz, respectively. The optical transmittance of the film is close to 100% at the wavelength of 550 nm. Scanning electronic microscopy (SEM) observation reveals that the microstructures, grain sizes and thicknesses of the thin films strongly dependent on the substrates, that is, the Pt/Ti/SiO2/Si substrate provides a more suitable interface layer than ITO/glass substrate for the growth of Bi4Ti3O12 thin films. The energy dispersive spectrometer (EDS) results indicate that the Bi/Ti atomic ratio of the films is less than that of target, which suggests that evaporation loss of bismuth occurs during the heating process. Whereas, this phenomenon occurs near the surface of thin film, it is not apparent in the inner of film. Excess 4wt% Bi2O3 additive in the target or additional Bi2O3 powder in the annealing process can compensate the loss of bismuth in the films, and improve the characteristics of thin films. Finally, the interdiffusion and chemical reactions take place among the element Bi, S and O at the interface during the deposition of ZnS:TbOF on Bi4Ti3O12 films, which degrades the optical transmittance of thin films. A 100 nm SiO2 buffer layer sandwiched between the ZnS:TbOF and Bi4Ti3O12 films can prevent the interdiffusion of the two layers, and enhance the optical transmittance and dielectric breakdown of Bi4Ti3O12 films.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references. Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Drexel University, 2003. / Includes abstract and vita. Includes bibliographical references (leaves 145-152).

There is a strong desire to develop new, advanced materials that can overcome the scaling difficulties present in current memory devices. Organic materials are promising candidates for resistive switching memory devices due to their low-cost advantage, simplified manufacturing process, compatibility with flexible electronic devices, and ease of being constructed cross-point cell array architecture. The operation of these types of devices requires change of device resistance when subjected to an electrical bias. We study three different systems that can achieve this requirement, wherein one is believed to be related to the charge storage in metallic trapping site, inducing space-charge field, inhibiting the charge injection; another exhibits negative differential resistance (NDR) characteristics; and the electrical transition of the third one is believed to be attributed to the formation of filaments. / text

Solar cells have been traditionally developed for optimizing three key steps for charge carriers: generation, separation, and transport. Conventional solar cells are essentially PN junction based, and utilize the internal electric field near the junction interface for realizing charge carrier separation. However, this kind of structure limits material choices and device fabrication to form a working junction due to issues such as lattice mismatch, doping, and band alignment. Ferroelectric photovoltaic devices with typical capacitor structure have been developed to overcome the junction caused disadvantage but suffer from the poor charge transport issue. In this work, novel ferroelectric-semiconductor photovoltaic devices were developed and investigated in detail with experimental results and theoretical simulation. This type of solar cell is fundamentally different with traditional PN junction based solar cells, utilizing ferroelectric polarization for charge separation in semiconductor layer. Systematical works have been conducted on: (1) device working principle and mechanism study; (2) effect of electrode; (3) influence of device key dimension parameters. The new cells showed the rectifying behavior and effective photovoltaic effect after specific asymmetric polarization. Furthermore, the device performance has been improved through adjusting electrode design and semiconductor layer thickness, which is mainly due to the optimized electric field strength and distribution resulting from polarization. As low cost commercial semiconductor, the multicrystalline silicon (mc-Si) has great potential application in the novel ferroelectric-semiconductor photovoltaic devices. However, the grain boundaries with high density of defects limit the material electric properties. In order to improve the multicrystalline silicon transport property, a polar molecules system was developed to play the role in grain boundaries passivation. The small polar molecule composition and solution passivation process were carried out to optimize the passivation effect. The result showed the developed ZK series solutions reduced the Rsheet across large-angle grain boundaries by up to more than one order to be close to the bulk Rsheet. Also, the correlation between the grain misorientation and passivation effectiveness was built up. / published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

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Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Apr. 9, 2009). PDF text: xvii, 113 p. : ill. (some col.) ; 3 Mb. UMI publication number: AAT 3339351. Includes bibliographical references. Also available in microfilm and microfiche formats.