Optimization of thin film uniformity is an important aspect for large-area coatings, particularly for optical coatings where error tolerances can be of the order of nanometers. Physical vapor deposition is a widely used technique for producing thin films. Applications include anti-reflection coatings, photovoltaics etc. This paper reviews the methods and simulations used for improving thin film uniformity in physical vapor deposition (both evaporation and sputtering), covering characteristic aspects of emission from material sources, projection/mask effects on film thickness distribution, as well as geometric and rotational influences from apparatus configurations. Following the review, a new program for modelling and simulating thin film uniformity for physical vapor deposition was developed using MathCAD. Results from the program were then compared with both known theoretical analytical equations of thickness distribution and experimental data, and found to be in good agreement. A mask for optimizing thin film thickness distribution designed using the program was shown to improve thickness uniformity from ±4% to ±0.56%.

Surface Enhanced Raman Spectroscopy presents a rapid, non-destructive method to identify chemical and biological samples with up to single molecule sensitivity. Since its discovery in 1974, the technique has become an intense field of interdisciplinary research, typically generating >2000 publications per year since 2011. The technique relies on the localised surface plasmon resonance phenomenon, where incident light can couple with plasmons at the interface that result in the generation of an intense electric field. This field can propagate from the surface from the metal-dielectric interface, so molecules within proximity will experience more intense Raman scattering. Localised surface plasmon resonance wavelength is determined by a number of factors, such as size, geometry and material. Due to the requirements of the surface optical response, Ag and Au are typical metals used for surface enhanced Raman applications. These metals then need to have nano features that improve the localised surface plasmon resonance, several variants of these substrates exist; surfaces can range from nanoparticles in a suspension, electrochemically roughened electrodes to metal nanostructures on a substrate. The latter will be the focus of this review, particularly reviewing substrates made by oblique angle deposition. Oblique angle deposition is the technique of growing thin films so that the material flux is not normal to the surface. Films grown in this fashion will possess nanostructures, due to the atomic self-shadowing effect, that are dependent mainly on the deposition angle. Recent developments, applications and highlights of surface enhanced Raman scattering substrates made by oblique angle deposition will be reviewed.

TiO₂ deposition using separate regions for sputtering and oxidation is not well investigated. We optimized process parameter for such as oxygen flow and microwave power to produce high quality TiO₂ filters for Stereo/3D imaging applications. This deposition technique was chosen for its unique advantages: high deposition rates while increasing the probability of obtaining stoichiometric oxides, reduces possibility of target poisoning and provides better stability of process. Various characterization methods, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman, X-ray diffraction (XRD), transmission spectroscopy, were used in compliment to simulations for detailed analysis of deposited TiO₂ thin films. Process parameters were optimized to achieve TiO₂ films with low surface scattering and absorption for fabricating multi-passbands interference filter for 3D glasses. From observations and quantitative analysis of surfaces, it was seen that surface roughness increases while oxygen flow or microwave power increases. As the content of anatase phase also increases with higher microwave power and higher oxygen flow, the formation of anatase grains can cause higher surface roughness. Optical analysis of samples validates these trends and provided additional information for absorption trends. Optimized parameters for deposition process are then obtained and the final fabricated 3D glasses filters showed high match to design, within 0.5% range for thickness error.

Magnesium fluoride (MgF₂) materials are commonly used for near/medium infrared anti-reflection optical coatings due to their low refractive index and wide-range transparency. Ion assistant deposition is an important technique to increase the density of MgF₂ and reduce absorption around 2.94 µm caused by high porosity and moisture adsorption. However, the excessive energy of Argon ion will induce a color center and; therefore, lead to UV/Visible absorption. In this paper, oxygen ion was introduced to reduce the color center effect in MgF₂ thin film deposited using electron beam evaporation with ion assistant. The films were deposited on Bk7 and single crystal silicon substrates under various oxygen ion beam currents. The microstructure, optical constant, film density, stress, and adhesion are investigated, including the absorption properties at the infrared hydroxyl (–OH) vibration peak. The results show that as the oxygen ion beam current increases, the absorption value at the position of the infrared OH vibration, defects, and stress of the film decrease, while the refractive index increases. However, MgF₂ has poor adhesion using oxygen ion-assisted deposition. Thin MgF₂ film without ion beam assistant was used as adhesive layer, high density, and low absorption MgF₂ film with good adhesion was obtained.

High precision, single-wavelength optical monitoring of reflectance was shown to be useful in the study of initial oxidation of very thin metal films by low pressure oxygen at room temperature. Thin films of Al, Ni, and Hf metal were sputter-deposited on silicon substrates and their subsequent oxidations were observed at low oxygen partial pressure using a temperature-stabilised laser diode reflectometer. Based on the derived properties of the appropriate metal and oxide films, optical monitoring data were fitted as a multilayer stack comprised of oxide/metal/SiO2/Si. The fitting results show that the exposure to oxygen at a partial pressure of 0.04 Pa forms a certain finite thickness of oxide film on the metal surface. A range of kinetic models such as Deal-Grove, Massoud, and Cabrera-Mott are commonly used to describe the surface oxidation process. However, these models cannot be applied to the initial stage of oxidation, which occurs when a pure metal surface is exposed to oxygen as measured here. Instead, simple chemical reaction kinetics is used to model the time-dependent experimental results of the early stages of oxidation, thus we obtain the equation d(t) = do[1-exp(-t/τ )] and d(t) = do[1-1/(1+t/τ )] for the gas environments of this investigation.