No description available.

Thesis (Ph. D.)--Lehigh University, 2001. / Includes bibliographical references and vita.

Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references [p. 133-146) Also available via World Wide Web.

Thesis (M.S.)--School of Materials Science and Engineering, Georgia Institute of Technology, 2005. Directed by Christopher Summers. / Summers, Christopher, Committee Chair ; Snyder, Robert, Committee Member ; Wang, Zhong Lin, Committee Member. Includes bibliographical references.

The development of materials for optical thin film application is essential to progress in fields such as optical data storage and signal processing. Samarium sulfide (SmS) thin films were prepared by reactive evaporation of samarium in hydrogen sulfide (H₂S). These displayed optical switching properties despite the presence of large amounts of carbon and oxygen. They are therefore potentially useful for data storage. The semiconductor to metal phase transition was characterized by x-ray diffraction and spectrophotometry. The observed optical response was modelled by a Bruggeman effective medium calculation. Success with this analysis suggests it as a means for predicting performance in subsequent applications. Zinc sulfide (ZnS) thin films were prepared by molecular beam epitaxy (MBE). Implimentation of an H₂S treated silicon surface provided good chemical bond match in addition to a good lattice match. Atomic layer epitaxy was unsuccessfully explored as a means to grow ZnS from zinc and H₂S reactants, therefore other reactants are proposed. Both the MBE and ALE work is directed at the long term goals of producing p-type ZnS, which is suitable for semiconductor lasing at short wavelengths, and high quality SmS thin films.

Materials in the form of thin films that have been deposited from the vapor phase are significantly different from similar bulk materials, both optically and mechanically, because of their columnar structure and consequent porosity. Their porosity have been verified in different ways. The effects of the pores on optical and mechanical performance and, in particular, the influence of water adsorption, have also been demonstrated. Three techniques used for investigating optical instabilities in thin films are given. They all involve sharp resonances. The resonances are associated either with surface plasmons, metal-dielectric narrowband filters, or all dielectric narrowband filters. These resonances are very sensitive functions of layer properties and hence can be used to detect and measure changes in the layers, particularly those that are induced by adsorption of moisture. Moisture adsorption in thin films is a complex process that occurs unevenly in patches. Using resonance techniques, the adsorption isotherms of change in refractive index, of growth rate in patch size, and of peak wavelength shift, which are all important in characterizing the porosity of films, have been measured. Some effects that locally increase film porosity and create central pores that permit water to penetrate into multilayer structures have been investigated. Based on these results, some suggestions for preventing water adsorption in films are then made. Moisture penetration into thin film structures is the major source of optical coating instability and it is therefore very important that the mechanisms of penetration by understood. Some deductions of the mechanisms are made from the experimental results.

We established measurement and analysis techniques necessary to investigate the optical properties of some transition metal compounds: specifically the carbides and nitrides of Ti, Zr, and Hf. Two distinct techniques determined the optical constants of these films: a Nestell-Christy method to invert measurements of thickness, reflection, and transmission and a Kramers-Kronig analysis of reflection. The compositions of the samples were evaluated by X-ray diffraction, Auger spectroscopy, scanning electron microprobe analysis, and nuclear analysis. We found it possible to correlate these materials' optical and electronic properties and relate these to compositional changes. The ability to engineer a specific optical response of materials is discussed. Additions of carbon and nitrogen change the optical properties in a specific manner; the roles of these elements as electron donors and their effect on the location and population of the d electron bands with respect to the Fermi level are postulated.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

To augment the monitoring capabilities of a Balzers 760 coating chamber, we replaced the simple, single wavelength optical monitor with a wide-band scanning monochromator system which records transmission data over the visible region of the spectrum. The system is controlled by an IBM-PC. The same computer is also interfaced to a quartz crystal monitoring system which was purchased with the Balzers chamber. The scanning monochromator system required a new brighter light source to deliver sufficient signal to the detector array through the more complex, dispersive optical train. Above the chamber the filter and the photomultiplier pair were removed, and replaced by a flat mirror which diverts the beam horizontally into the scanning monochromator system. The beam passes first through a telescope-slit configuration onto a Jobin-Yvon holographic grating, built to disperse the 400-800 nm band of which we use approximately 360 nm. This reflective grating images the spectrum of the slit onto a Fairchild CCD array, which consists of 1728 elements. These elements are then averaged into 173 data points and recorded by the IBM-PC. The 173 data points allows us a wavelength resolution of about 2 nm. The IBM incorporates a Tecmar A/D board in accepting data from both the quartz crystal monitor and the scanning monochromator system. Although the system is capable of recording data at a faster rate, it is generally stored once every three seconds. This is adequate since at normal deposition rates this gives us information every 10 - 20 Angstroms of deposited material. The system has been used in several applications which will be discussed in this dissertation. They include in situ measurements of water adsorption into a film, derivation of optical constant profiles during the film deposition, both of which may lead us to a better understanding of the growth of a thin film. The monochromator has also been used to analyze the components of a multilayer coating by monitoring the film's transmission spectra while it was sputter-etched off. The extension of the system into the ultraviolet region of the spectrum and some future applications are also considered.

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