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In this thesis we investigate theoretically various types of sculptured thin film (STF) envisioned as platforms for optical sensing. A STF consists of an array of parallel nanowires which can be grown on a substrate using vapour deposition techniques. Typically, each nanowire has a diameter in the range from ~ 10-300 nmwhile the film thickness is ~<1μm. Through careful control of the fabrication process, both the optical properties and the porosity of the STF can be tailored to order. These abilities make STFs promising for optical sensing applications, wherein it is envisaged that the material to be sensed infiltrates the void region in between the parallel nanowires and hence changes the optical properties of the STF. Various homogenization formalisms can be used to estimate the constitutive parameters of the infiltrated STFs. In this thesis two different homogenization formalisms were used: the Bruggeman formalism (extended and non–extended versions) and the strong-permittivityfluctuation theory (SPFT). These were used in investigations of the following optical–sensing scenarios: (i) Electromagnetic radiation emitted by a dipole source inside an infiltrated chiral STF. The effects of using the extended Bruggeman homogenization formalism, which takes into account the nonzero size of the component particles,were studied. (ii) Surface–plasmon– polariton waves on ametal–coated, infiltrated columnar thin film. The influences of using the extended SPFT formalism, which takes into account the nonzero size of the component particles and their statistical distributions, were explored. (iii) A metal-coated infiltrated chiral STF which supports both surface-plasmon-polariton waves and the circular Bragg phenomenon. The possibility of using in parallel both surface-plasmon-polariton waves and the circular Bragg phenomenon was investigated using the non–extended Bruggeman formalism. Our numerical studies revealed that the design performance parameters of the infiltrated STF are bode well for these optical–sensing scenarios. The use of inverse Bruggeman formalism was also investigated: this was found to be problematic in certain constitutive parameter regimes, but not those for optical–sensing scenarios considered in this thesis.

Approved for public release; distribution is unlimited / Large shear stresses often develop at the interface between dissimilar materials in microelectronic devices, when they are subjected to thermo-mechanical excursions. These stresses can facilitate diffusionally accommodated interfacial sliding, or creep. A driving factor for these stresses is the thermal expansion mismatch between the adjoining materials. For narrow thin film lines, these stresses may exist over a large fraction of the film-substrate interface. This thesis explores methodologies to measure the kinetics of interfacial creep at model Al thin film/silicon substrate interfaces. A method of sample production, which involved diffusion bonding a polished Si substrate to the surface of a thin Al film deposited on a second Si substrate was developed (Si/Al/Si sandwich). When loaded edge-wise in compression, the Al thin film - Si interface are loaded in shear. By measuring the relative displacements between the two Si substrates, the interfacial displacement rates at varying temperatures and stresses were experimentally determined. In accordance with previous results, the kinetics was given by a diffusional creep law with a threshold stress, and an activation energy representing interfacial diffusion. The activation energy was found to be unusually low, and further experimental and modeling studies are needed to better understand its origin. / Lieutenant Commander, United States Navy

by Leung Yat-chor, Calvin. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

by Tse Pak Kan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Tse Pak Kan. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.iv / TABLE OF CONTENTS --- p.v / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xiii / Chapter CHAPTER 1 --- DIAMOND AND DIAMOND-LIKE CARBON FILMS - BACKGROUND --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Properties of diamond and diamond like carbon --- p.1 / Chapter 1.2.1 --- Nature of diamond film --- p.1 / Chapter 1.2.2 --- Nature of diamond-like carbon films --- p.3 / Chapter 1.2.2.1 --- Diamond-Like Carbon Films --- p.6 / Chapter 1.2.2.2 --- Diamond-Like Hydrocarbon Films --- p.7 / Chapter 1.3 --- Application of diamond films --- p.8 / Chapter 1.4 --- Application of diamond-like carbon films --- p.9 / References for Chapter1 --- p.11 / Chapter CHAPTER 2 --- BACKGROUND OF THE STUDY --- p.12 / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Chemical Vapor Deposition --- p.15 / Chapter 2.2.1 --- CVD techniques --- p.17 / Chapter 2.2.2 --- Drawback of CVD techniques --- p.17 / Chapter 2.3 --- Ion beam Deposition --- p.18 / Chapter 2.3.1 --- Ion beam deposition techniques --- p.18 / Chapter 2.3.2 --- Literature review of ion beam deposition of diamond films --- p.19 / Chapter 2.3.2.1 --- Homoepitaxy of diamond films --- p.20 / Chapter 2.3.2.2 --- Heteroepitaxy of diamond films --- p.21 / Chapter 2.4 --- Objective of the present study --- p.23 / References for Chapter2 --- p.25 / Chapter CHAPTER 3 --- INSTRUMENTATION --- p.27 / Chapter 3.1 --- Introduction --- p.27 / Chapter 3.2 --- Low energy ion beam deposition system (LEIBS) --- p.27 / Chapter 3.2.1 --- Introduction --- p.27 / Chapter 3.2.2 --- Theory --- p.28 / Chapter 3.2.3 --- System Operations --- p.29 / Chapter 3.2.3.1 --- Ion Source --- p.30 / Chapter 3.2.3.2 --- Electrostatic Einzel Focusing Lens --- p.33 / Chapter 3.2.3.3 --- Auxiliary hot electron emitter --- p.33 / Chapter 3.2.3.4 --- Substrate stage with a heater block --- p.35 / Chapter 3.3 --- X-ray photoelectron spectroscopy (XPS) --- p.35 / Chapter 3.3.1 --- Background of XPS --- p.35 / Chapter 3.3.2 --- Theory --- p.35 / Chapter 3.3.3 --- Qualitative analysis --- p.39 / Chapter 3.3.3.1 --- Chemical Shift Peaks --- p.42 / Chapter 3.3.3.2 --- Auger Peaks --- p.43 / Chapter 3.3.3.3 --- Energy Loss Peaks --- p.43 / Chapter 3.3.4 --- Quantitative analysis --- p.44 / Chapter 3.3.4.1 --- Homogeneous system --- p.44 / Chapter 3.3.4.2 --- Layer Thickness Determination --- p.49 / Chapter 3.3.5 --- Instrumentation --- p.51 / Chapter 3.3.5.1 --- Monochromatized X-ray source --- p.53 / Chapter 3.3.6 --- Application to carbon films --- p.54 / Chapter 3.3.6.1 --- Compositional Analysis --- p.54 / Chapter 3.3.6.2 --- Angle-resolved analysis --- p.56 / Chapter 3.3.6.3 --- Energy Loss Structure --- p.58 / References for Chapter3 --- p.61 / Chapter CHAPTER 4 --- THE CHARACTERIZATION OF LOW ENERGY ION BEAM USING A COMPACT FARADAY CUP --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- Design of the Faraday cup with retarding lens --- p.63 / Chapter 4.3 --- Parameters control of energy distribution of ion beam --- p.66 / Chapter 4.4 --- Basic operation of the retarding lens energy analyser --- p.67 / Chapter 4.5 --- Effect of cathode voltage on energy distribution --- p.68 / Chapter 4.6 --- Effect of anode voltage on energy distribution --- p.71 / Chapter 4.7 --- Effect of sample bias on energy distribution --- p.71 / Chapter 4.8 --- Conclusions --- p.71 / References for Chapter4 --- p.76 / Chapter CHAPTER 5 --- OPTICAL PROPERTIES OF DLC FILMS DEPOSITED --- p.77 / Chapter 5.1 --- Introduction --- p.77 / Chapter 5.2 --- Experimental Procedure --- p.78 / Chapter 5.2.1 --- Sample pretreatment --- p.78 / Chapter 5.2.2 --- Improvement of current density --- p.80 / Chapter 5.2.3 --- Improvement of charging effect --- p.80 / Chapter 5.2.4 --- Experimental Plan --- p.82 / Chapter 5.3 --- Determination of thickness and growth rate of DLC films by alpha-step instrument --- p.83 / Chapter 5.4 --- Determination of microstructures in DLC films by Raman spectroscopy --- p.86 / Chapter 5.5 --- Determination of sp3/sp2 ratios in DLC films by infrared spectroscopy --- p.91 / Chapter 5.6 --- Determination of band gap of DLC by ultraviolet-visible transmittance spectrum --- p.94 / Chapter 5.7 --- Conclusions --- p.97 / References for Chapter5 --- p.99 / Chapter CHAPTER 6 --- GROWTH OF DIAMOND AND DIAMOND-LIKE FILMS USING DIFFERENT ION ENERGIES --- p.100 / Chapter 6.1 --- Introduction --- p.100 / Chapter 6.2 --- Experimental Procedure --- p.100 / Chapter 6.2.1 --- Sample pretreatment --- p.100 / Chapter 6.2.2 --- Improvement of heating source --- p.100 / Chapter 6.2.3 --- Experimental Plan --- p.101 / Chapter 6.3 --- Characterization of carbon films using XPS --- p.102 / Chapter 6.4 --- XPS-EELS of carbon films under different ion beam energy --- p.102 / Chapter 6.5 --- Surface morphology of carbon films --- p.106 / Chapter 6.6 --- Mechanism proposed --- p.108 / Chapter 6.7 --- Conclusions --- p.109 / References for Chapter6 --- p.111 / Chapter CHAPTER 7 --- INVESIGATION OF ADHESION PROPERTIES OF PERFLUORINATED LUBRICANTS ON AMORPHOUS CARBON OR CARBON NITRIDE FILMS --- p.112 / Chapter 7.1 --- Introduction --- p.112 / Chapter 7.2 --- Experimental Procedure --- p.113 / Chapter 7.2.1 --- Description of perfluorinated lubricant used --- p.113 / Chapter 7.2.2 --- Determination of the composition of a-C:H or CNX layer --- p.116 / Chapter 7.2.3 --- Thickness calculation --- p.116 / Chapter 7.3 --- Characterization of PFPE film --- p.121 / Chapter 7.4 --- Effects of molecular weight of PFPE on lubricant adhesion --- p.125 / Chapter 7.5 --- Effects of hydrogen content on lubricant adhesion --- p.128 / Chapter 7.6 --- Effects of end groups of PFPE on lubricant adhesion --- p.128 / Chapter 7.7 --- Verification of film thickness --- p.129 / Chapter 7.8 --- Conclusions --- p.129 / References for Chapter7 --- p.131 / Chapter CHAPTER 8 --- CONCLUSIONS --- p.132

Calcium aluminate compound, 12CaO.7Al2O3, was prepared via an improved sol-gel technique in the form of thin film on magnesium oxide (MgO) single crystal substrate as well as powder. The microstructures of the films were observed before and after crystallization, and the effect of solution processing parameters, including the molar fractions of the ingredients, on the continuity of the films and the formation of surface defects was studied. An optimized sol-gel process using a new solution recipe was developed based on the microstructural observations. Homogeneous thin films of 12CaO.7Al2O3 with high critical thickness (~ 5 − 6 μm)were produced using this optimized technique. The chemical composition of the films was determined using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Raman and Fourier transform infrared (FTIR) spectral analyses were employed in order to investigate the effect of heat treatment temperature on the crystallization of 12CaO.7Al2O3 film on magnesium oxide substrate. The results of the phase analysis show that a single-phase film of 12CaO.7Al2O3 is formed at a temperature of 1300 oC. A crystallized structure with well-defined grain boundaries is obtained after 2 hr of heat treatment at this temperature under normal air atmosphere. The phase formation of 12CaO.7Al2O3 in powder form was investigated via room-temperature and high-temperature X-ray diffraction (XRD) and crystallization of 12CaO.7Al2O3 and CaO.Al2O3 powders started taking place simultaneously at a temperature of ~ 900 oC. A comparison between the FTIR results of the films with XRD results of the powder proved the crystallization of 12CaO.7Al2O3 thin film to start at a higher temperature compared to the powder. Furthermore, a single-phase 12CaO.7Al2O3 tends to form in thin film on MgO substrate, whereas the formation of 12CaO.7Al2O3 is accompanied by the formation of secondary phases of CaO.Al2O3 and 3CaO.Al2O3. The optical absorption properties of the 12CaO.7Al2O3 films were investigated at different temperatures from room temperature to 300 oC and the experimental data were analysed in Tauc and Urbach regions. The optical band gap decreased from 4.088 eV at 25 oC to 4.051 eV at 300 oC, while Urbach energy increased from 0.178 eV at 25 oC to 0.257 eV at 300 oC. The relationship between the optical band gap and the Urbach energy at different temperatures showed an almost linear relationship from which the theoretical values of 4.156 and 0.065 eV were evaluated for the band gap energy and Urbach energy of a 12CaO.7Al2O3 crystal with zero structural disorder at 0 K.

This dissertation is centered on investigation of metastable thermoelectric thin film materials and is split into 3 primary sections. Section 1 focuses on formation mechanisms of FeSbx compounds from layered precursors. It was found that a compositionally favorable and homogeneous nucleation environment allowed for the nucleation of a metastable phase, which surprisingly resembles the local coordination environment of the precursors, even in cases where they are compositionally unfavorable. Over the course of this work, the technique of normal-incidence thin film pair distribution function analysis is introduced, which allows for rapid acquisition and analysis of local structure data from intact thin films. Section 2 investigates changes in the stacking sequences of ([PbSe]1+δ)m(TiSe2)n nanolaminate materials, which consist of interleaved layers of each compound in the chemical formula, and how these changes effect the thermoelectric power factor. Homologous series of systematically varying m and n values are investigated and measured properties are correlated back to the designed nanoarchitecture of the laminate materials. It is found that the compounds are stabilized by electron exchange between constituents at the interfaces, and that ‘doping’ of the laminate structure by changing the relative amounts of each constituent is an effective means of optimizing their transport properties. It is also shown that interface density between constituents can be utilized to optimize performance. Section 3 moves from the case of PbSe layers, which maintain their structure, to SnSe layers that significantly distort as the layer size is changed. The distortions in SnSe are observed to occur from templating off TiSe2 layers. As the size of the SnSe layers increases, relatively fewer templated interfacial atoms exist and stabilization of interior atoms must also be considered. The coarse behaviors developed in ([PbSe]1+δ)m(TiSe2)n hold, but the structural distortions in SnSe likely change the band structure of this constituent and hence the composite material, complicating the analysis. In some cases, these changes allow for radically different behavior, best exemplified with high TiSe2 ratios in ([SnSe]1+δ)1(TiSe2)n displaying significant enhancement of the Seebeck coefficient at cryogenic temperatures over the low-n and PbSe-containing analogues. This dissertation includes previously published and unpublished coauthored material.