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The properties of the lead ohaloogenide group of semiconductors and more specifically of PbTe, have been investigated in order to predict, and control the growth of thin epitaxial films for use as thin film field effect transistors. The thermodynamic properties of binary compounds has been analysed in detail and used to explain the defect properties of PbTe and PbSe. The calculated pressure-temperature-composition (or P-T-x) phase diagram for PbTe was compared with "as grown" and annealed epitaxial film properties (grown on mica substrates) to discover whether films obeyed bulk thermodynamics. "As grown" films appear to be metastable, i.e. their composition, estimated from electrical properties, suggests that they lie outside the phase boundary at the substrate temperatures employed (200-300°C). Changes occur on annealing in vacuo which suggest that the films tend toward the thermodynamic equilibrium state represented, by the calculated bulk P-T-x phase diagram. An investigation of the electrical properties of ternary solid solutions of group IX elements with PbTe and PbSe has been carried out in the hope of producing an improved semiconductor material compared with PbTe and PbSe. A correlation of electrical properties with film structure, obtained from replication and transmission elctron microscopy, was attempted producing a number of useful and interesting conclusions.

This thesis describes the work carried out by the author into the preparation, and measurement of magnetic properties, of monocrystalline cobalt thin films. Monocrystalline cobalt thin films were grown by vapour deposition in a vacuum onto the {100} faces of magnesium-oxide single crystal substrates . The crystallographic structure of the cobalt thin films on the MgO substrates was investigated using reflection X-ray diffraction and reflection high energy electron diffraction. The epitaxy of the cobalt on the MgO substrates was found to depend on the substrate deposition temperature. The epitaxial temperature required to produce monocrystalline cobalt films on the {100} faces of MgO was found for the author's deposition apparatus. A torque magnetometer was constructed by the author in order to determine the magnetic anisotropy of the cobalt thin films. It was found that the apparent film magnetic anisotropy was closely correlated to the substrate temperature during the deposition of the films, and hence to the crystallographic state of the films.

The work is aimed at investigating the effects of charged particle bombardment on the preferential deposition of thin films so that knowledge may be gained regarding the feasibility of 'writing' interconnection patterns with programmed ion beams. Some theories of thin film nucleation are reviewed and comparisons made between two recent models that show their compatibility for the limited condition where the stable nucleus contains two atoms. Nucleation experiments involving silver on silicon oxide are described and the results compare well with theory. Values of surface energy are derived and estimates of fundamental vibration frequencies made. (E[alpha] ~ 0.3 eV E[d], ~ 0.1 eV and nu[1], and nu[c] ~ 10 sec[-1]). Critical condensation experiments are described that reinforce the value of obtained by the nucleation studies. Calculations of E[?] are made for a variety of elements on silicon oxide and their condensation energies are estimated and conclusions drawn regarding suitable condensates and dopants for preferential deposition sensitization. Development of an ion source and simple ion optical system for preferential deposition studies is described and results of ion energy spread measurements are given. The trapping probabilities of gold ions into silicon oxide are measured and compared with a theoretical model. These results and further experiments allow the minimum A[+] ion dose for inducing the preferential deposition of silver to be established over the energy range 70-350 eV. A model is proposed based on three dimensional cluster formation by extending already discussed and verified nucleation theory. The cluster formation is assumed to extend to the maximum range of the implanted ions and semi-quantitative agreement is found between this theory and experiment. Finally some experiments are described in which electrons are shown to promote preferential deposition on pure SiO[2] but not on evaporated SiO. A qualitative model based on the existence of neutral traps is proposed to account for the results. It is concluded that providing suitable ion optics can be developed the process of 'writing' interconnection patterns is feasible. Appendices deal with abortive condensation energy measurements, extension of data obtained to forecast the high energy implanted doses required for preferential deposition and the effects of ion bombardment on thin film adhesion.

The purpose of this study has been to investigate the possibilities of doping cadmium telluride CdTe by the technique of ion implantation. Crystals grown by different techniques have been implanted with hydrogen, argon, indium, tellurium and bismuth ions at energies which produce lattice disorder to a mean depth of about 300 A. Electrical activity generated in implanted layers has been studied as a function of ion type, dose, implantation temperature and annealing temperature. The lattice disorder in these layers has also been investigated as a function of implanted ion energy, and dose rate. Measurements using the thermal probe, sheet resistivity and Hall effect techniques have been taken to assess material suitable for implantation and to investigate electrical activity in implanted layers. Damage centres in the CdTe bandgap have been investigated as a function of ion type and annealing temperature, using the Thermostimulated current technique. The Rutherford Backscattering and channelling of alpha particles has been applied to all implanted material to yield information about the amount and distribution of lattice disorder. The technique also gave information on the position of implanted bismuth in the CdTe lattice. Lattice disorder, produced by the above heavy .ions, exhibited annealing characteristics which were dependent on dose and implant conditions. Complete reordering of the lattice was not detected, due to surface evaporation above 450°C. Bismuth ion movement was detected but no substitutional component was observed. On annealing above 450°C implanted bismuth was rapidly lost from the surface. Besides the generation of radiation induced trapping levels, no electrical activity was detected in samples implanted at room temperature. Implanting indium into substrates held at 200°C produced a dose dependent activity and in the best case one in three of the implanted indium ions became electrically active.

In this work, physical characterisation of film formation and film properties of coating and adhesive formulations was performed. Organic/inorganic nanocomposite coatings draw remarkable academic and industrial interest, due to their expected enhancement of combined properties. Film formation and film properties, such as drying, transparency, and final film quality of coating systems containing Laponite clay were studied, in particular the influence of excess surfactant on the drying process. It was found that excess surfactant in the system does affect the physical characteristics of the film formation process. Experiments using magnetic resonance profiling and photographs found lateral flow of liquid from the edges to the centre. Reducing the amount of surfactant in the system improves film quality by reducing lateral flow during film formation. In pressure sensitive adhesive (PSA) applications, such as labels or tapes, it is vital that the films remain optically transparent, regardless of the exposure to high humidity or water. Core/shell PSAs were investigated to determine their drying, water whitening, moisture absorption from high humidity, and adhesive properties. The dependence of these properties on pH and poly (acrylic acid), PAA, was studied. It was found that the hydrophilic pathways created by PAA shells do not contribute to faster drying. In addition, this investigation disproves the idea that a "hairy layer" of PAA keeps the film more open and leads to faster drying. It was found that films with hydrophilic boundaries absorbed more water. The water is evenly distributed along the boundaries, so that films still retain their transparency. It was proved that transparency or water whitening is not necessarily a reliable measurement of water uptake, at least for this system. The findings from this study define guiding principles for organic/inorganic nanocomposite coatings and core/shell PSAs, to have better film formation characteristics and film properties.

The work has been directed towards the investigation of the ion implantation doping effects in thin metal and dielectric films so that knowledge may be gained regarding the feasibility of using ion implantation to produce active and passive thin film devices for microcircuits. Measurements concentrated on the detailed conduction properties, structure and composition of the films at varying stages of the ion implantation doping processes. Aluminium and titanium thin films are implanted with oxygen atoms to ion doses of about 1017 ions cm-2. During implantation the films' resistivitess change from that of metal to that of a dielectric. Electron microscope and electron diffraction observations show that as the oxygen dose is increased then metal-oxide clusters form and grow eventually reaching 200 - 300 A. in diameter. The film then consists of a metal/metal oxide matrix and the process of electronic conduction is an activated one, with activation energies of about 0.30 eV for the aluminium/aluminium oxide system and about 0.25 eV for the titanium/titanium oxide system. Evaporated silicon oxide films are doped with aluminium and titanium atoms by the process termed 'recoil atom implantation. This method of doping thin films is shown by use of radioactive measurements to be an effective and efficient method provided the film thickness is less than about 500 A. As the metal atom concentration in the dielectric is increased the resistivity of the film decreases from that of an insulator to that of a metal showing a positive temperature coefficient of resistance. Electron microscopy and electron diffraction studies show that the metal atoms form clusters within the dielectric matrix producing metal/SiO cermet type structures. The conduction properties of the implanted films are explained at low electric field strengths on a conduction model incorporating thermionic emission and quantum mechanical tunnelling mechanisms between homogeneous arrays of spherical metal particles in a dielectric matrix. This model yields potential barrier values, O°, of 0.92 eV and 0,80 eV for the aluminium/aluminium oxide and titanium/titanium oxide material respectively, formed by oxygen ion implantation, and values of 1,00 eV for the dielectric silicon oxide in the case of metal atom implantation. At high electric field strengths the conduction equations are modified by a Poole-Frenkel type emission over a field lowered potential harrier. This manifests itself in log I alpha F1/2andSE alpha F½ dependences, where I is the current, F the electric field and SE the activation energy for conduction. It is concluded that ion implantation can change in an accurate and reproducible way the electrical properties of thin metal and dielectric films and is a feasible method for producing thin film devices with a wide range of properties.

Experiments were carried out of scratching silicon slices with near (111) orientation, in and directions, by using two types of diamond indenters, at room temperature. Scratches have been investigated by optical and scanning electron microscopy, and X-ray topography. It is found that the appearance of the scratch and the wide residual strain field detected by diffraction contrast are both anisotropic with respect to direction, but in opposite senses; maximum chipping and wear is associated with minimum width of strain field for scratches in or near [112], [211] and [121] and vice versa for [112], [211] and [121]. It is concluded from a study of the topographic contrast in different reflections that the long-range field of residual elastic strain is in plane strain compression, and is associated with a system of cracks observed by optical microscopy. Scratches annealed in the range of temperatures (800°C- 1200°C) were examined by X-ray topography. It is found that no dislocation movement is detected in intrinsic silicon slices. Dislocation loops generated from scratches on the surface of slices doped with antimony and phosphorus. The greatest extent of glide occurs from the wide strain field of [112] scratches and the least from the narrow strain field of [112] scratches. Complete loops, and half loops of 60° dislocations have Burgers vectors lying in the plane of the slice in directions were studied. Slip lines have been observed along traces of (111) planes. A new technique has been developed to determine the misorientation angle from the (111) surface. A theoretical model of stress relaxation round a scratch is discussed. The results indicate that the activation energy for dislocation movement is ~ 0. 92 ev in the case of the [112] scratches, and ~ 1. 28 ev for [110] scratches. These figures agree roughly with the activation energies deduced from experiments in uniaxial tension on crystals orientated for single and double slip respectively. Growth features of metallic impurity were examined by (SEM) and (EPMA). Residual saw damage and contrast centres were observed by X-ray topography.

This work used a hydrophobic polymer pair, i.e. polystyrene (PS) and polyisoprene (PI), to construct well-organized polymer templates for the patterning of proteins through a selective adsorption process. This is a bottom-up method to pattern proteins. The nanopatterned protein surfaces were used as substrates to investigate cell adhesion behaviour. PS-b-PI copolymer ultrathin films formed well-ordered two-dimensional surface structures after spin-coating because of the confinement of substrate-polymer and polymer-air interfaces. A symmetric diblock copolymer film with an 18 nm thickness formed a structure with PI dots dispersed in a PS matrix, and an asymmetric diblock copolymer film of the same thickness formed a stripe-like structure. After incubating these templates in bovine serum albumin (BSA) solution, the ring-like and stripe-like protein nanopatterns were prepared, which resembled their underlying copolymer templates. ToF-SIMS confirmed that there is more BSA adsorption on the PS-b-PI template surface when there is more PS component exposed on the surface. Further, AFM and SIMS analysis confirmed that BSA molecules were localized on the PS domains rather than on the PI domains. The protein's selective adsorption is attributed to the great mobility of PI chains at room temperature. The PS, PI, PS-b-PI binary and ternary blends also formed a variety of structures. For thick films, the free surfaces of films are entirely covered by a thin PI layer because its surface energy is lower than PS. When the film thickness is less than 15 nm, both PS and PI components were exposed on the free surface. The resulting complicated surface structures also patterned BSA molecules. After an extracellular matrix protein, fibronectin (FN), was adsorbed on copolymer substrates, the ring-like and stripe-like FN nanopatterns were incubated in CHO cell suspensions. The ring-like FN pattern adhered more cells than the stripe-like and the control surfaces. The cells on the ring-like FN surface formed more actin fibers and spread better. This can be explained by the ring-like pattern increasing the FN ligand local density and further increasing the integrin clusters and focal adhesion. The ECM protein nanopattern has relevance for tissue engineering.

Most electro-reflectance experiments have been carried out in the visible and UV parts of the electromagnetic spectrum. Axe and Hammer (1967), however, are the only research workers who observed a qualitative modulation peak in the IR and in the vicinity of the reflectance plasma edge of Ge- and tin-doped GaAs. Large absorption corrections were required due to the absorption by the saturated methanol–NaCl electrolyte solution used. Their results were not reproducible, but indicate that a rather large effect should be expected. The scope of the work reported here was to extend ER studies associated with free electron effects into the near IR and obtain valuable quantitative results in order to develop and evaluate a microscopic theory.