A range of optical and optoelectronic applications would benefit from high refractive index (n), dense and transparent films that guide, concentrate and couple light. However, materials with high n usually have a high optical extinction coefficient (κ) which keeps these materials from being suitable for optical components that require long optical paths. We studied titanium hafnium oxide alloy films to obtain high refractive index (n>2) with minimum optical extinction coefficients (κ < 10−5) over the visible and near IR spectrum (380-930 nm). Titanium hafnium oxide alloys were deposited using pulsed DC reactive magnetron sputtering with and without RF substrate bias on silicon dioxide. For a given deposition condition intended for a specific titanium/hafnium molar fraction ratio, the ion energy of deposition species was explicitly controlled by varying the RF substrate bias. Spectroscopic ellipsometry, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS) and atomic force microscopy (AFM) were used to characterize the films. It appears that applying RF substrate bias reduces the nanocrystalline size, changes the surface morphology and increases the refractive index while maintaining comparable titanium/hafnium cation molar fraction. Precise control of the nanostructure of ternary metal oxides can alter their macroscopic properties, resulting in improved optical films.

Transparent conducting thin-films of SnO2: F were grown on preheated glass, Al2O3 coated glass, and quartz substrates by Streaming Process for Electrodeless Electrochemical Deposition (SPEED). Stannic chloride (SnCl4) and ammonium fluoride (NH4F) dissolved in a mixture of deionized water and organic solvents were used as precursors. The preheated substrate temperature was varied between 440 and 500 °C. High quality SnO2:F films were grown at all the substrate temperatures studied. The resulting typical film thickness was 250 nm. X-ray diffraction shows that the grown films are polycrystalline SnO2 with a tetragonal crystal structure. The average optical transmission of the films was around 93% throughout the wavelength range 400 to 1000 nm. The lowest electrical resistivity achieved was 6 × 10-4 Ω-cm. The Hall measurements showed that the film is an n-type semiconductor, with carrier mobility of 8.3 cm2/V-s, and carrier concentration of 1 × 1021 cm-3. The direct bandgap was determined to be 4.0 eV from the transmittance spectrum.

Stabilized Au NPs were directly deposited on nanostructured ZnO and ZrO2 by a simple one-step strategy based on sacrificial anode electrolysis. The annealed nanocomposites are proposed as active layers in resistive gas sensors for low-cost processes. Results on the performance of gas sensors based on pristine and Au-doped MOx nanostructured thin films, used for the detection of NO2 gas, were reported at an operating temperature of 300°C, evaluating the effects of the MOx chemical composition and morphology, and the Au-doping.

We report the investigation of ZnO thin films delta-doped with lithium and phosphorus introduced simultaneously. The films were deposited from high purity ceramic targets of ZnO and Li3PO4 on c-plane sapphire substrates by RF magnetron sputtering. An undoped ZnO film with a low background electron concentration was used as the buffer layer on the sapphire substrate. The doped films were prepared by carrying simultaneous sputtering from the ZnO and Li3PO4 ceramic targets. For uniform doped films, the simultaneous deposition from the ZnO and Li3PO4 was uninterrupted. For the delta-doped films on the other hand, deposition from the ZnO target was uninterrupted while that from the Li3PO4 was interrupted periodically using a shutter. Post-deposition annealing was carried using a rapid thermal processor in O2 at 900 oC for 3 min. Results obtained from photoluminescence spectroscopy measurements at 12 K revealed acceptor-related luminescence peaks at 3.35 eV, possibly due to the transition from exciton bound to a neutral acceptor. The x-ray diffraction 2θ-scans showed a single peak at about 34.4o. Hall effect measurements revealed p-type conductivities with an average Hall concentrations of 3.8 x 1013 cm-3 in uniform doped samples and 1.5 x 1016 cm-3 in delta doped samples. However, in some cases the Hall coefficients had both positive and negative values, making the determination of the carrier type inconclusive. The fluctuation in the carrier type could be due to the lateral inhomogeneity in the hole concentration caused by signal noise impacting the small Hall voltages in the measurements.

The role of ferroelectric LiNbO3 (LNB) in altering the frequency dependence of the capacitance of CaCu3Ti4O12 (CCTO) thin films has been investigated. A cost effective spin coating deposition process was used to integrate the oxide heterostructures onto silicon substrates. This study showed that the frequency stability of the CCTO/LNB structure was much improved when the crystallization conditions and physical dimension of each layer were optimized. To integrate this structure with current silicon technology, heterostructures of CCTO and LNB thin films were fabricated on HF terminated Si using chemical solution deposition. It was found that the order of deposition of the two layers was important for the structural quality of the heterostructures with the CCTO layer followed by the LNB layer being the preferred structure. In addition to improvement of the capacitance variation with frequency, the heterostructures also provide a path to tuning the frequency of operation.

Although the presence of oxygen reservoir is assumed in many theoretical models which explain resistive switching of ReRAM with an electrode/metal oxide (MO)/electrode structure, the location of oxygen reservoir is not clear. We have previously reported a method for preparing an extremely small ReRAM cell which has removable bottom electrode (BE), by using AFM cantilever. In this study, we used this cell structure to specify the location of oxygen reservoir. Since an anode is assumed to work as an oxygen reservoir in most models, we investigated the effect of changing anodes for the same filament on the presence or absence of the occurrence of reset switching. It was revealed that reset occurred independently of catalytic ability and Gibbs free energy (ΔG) of anode material. However, reset was caused by repairing oxygen vacancies of which filament consists when metals with high ΔG is used as an anode, whereas by oxidizing an anode when metals with low ΔG is used as an anode. This result suggests that the MO film works as an oxygen reservoir for anode with high ΔG, whereas an anode works as an oxygen reservoir for anode with low ΔG.

Micron-size talc samples were ground using a high-intensity planetary ball mill at different milling times as an attempt to reduce particle size and study the effect on the corresponding hydrophobicity. XRD and SEM results confirmed the decrease in the particle size. FTIR spectroscopy analyses revealed the talc characteristic bands centered on 669 cm-1 for the O-H bonds and 1018 cm-1 for the Si-O bonds, as well as a degradation in the talc structure for prolonged milling times. BET results indicate an increase of specific surface area, which also confirms particle size reduction, reaching a maximum at 1 h, after which the particles agglomerate. Contact angle measurements show a decrease in the hydrophobicity of talc after milling. Although talc retains its hydrophobicity after short milling periods, prolonged grinding causes the mineral to have a more hydrophilic character.

The Laser Intensity Modulation Method, LIMM, has been used to investigate the poling state of ceramic piezoelectric thin films. The frequency of the system has been extended to 70MHz to enable films of thicknesses down to 100nm to be measured. A unique development has been to sweep the DC bias applied to the sample whilst performing the LIMM measurement, thus giving pseudo PE loops. These PE loops are unique in that they represent the polarization state within a distinct depth of the film, whereas normally PE loops are a result of the complete film. This allows us to investigate processes occurring within different regions of the film.

Due to its wide band-gap, Al2O3 is known to have a moderate leakage current and a good dielectric strength [1]. Moreover, this dielectric has a fair permittivity and so constitutes interesting candidate as dielectric for Metal-Insulator-Metal (MIM) capacitor. Atomic Layer Deposition (ALD) allows obtaining a dense and thin Al2O3 amorphous layer. ALD limits problems of interlayer diffusion because Al2O3 is deposited underneath 400°C [2] which is essential when MIM are co-integrated with temperature sensitive structures.

The aim of our investigation is to attempt to tie aluminum oxide properties dielectric with reliability from the help of capacitors of the entire wafer. In this way, conduction mechanism analysis and capacitance measurements were statistically led on the wafer. We particularly focus our study on the quantification of defects and their influence on the leakage current in planar capacitor. Firstly, to estimate the fixed oxide charges densities in the bulk of Al2O3 and to analyze conduction mechanism, Metal-Oxide-Semiconductor (MOS) (Al/Al2O3/HR-Si) is developed. Then, a MIM stack (Al/TiN/Al2O3/TiN/HR-Si) is developed in order to evaluate the leakage current and the electrical reliability of thin films Al2O3 based MIM capacitors. Different performances are observed according to the area on the wafer. That could be explained by the quality of the Al2O3 layer and the interfaces between TiN and the oxide.

Optical components such as lenses, glass windows, and prisms are subject to Fresnel reflection due to the mismatch between the refractive indices of the air and glass. An optical interface layer, i.e., antireflection (AR) layer, is needed to eliminate this unwanted reflection at the air/glass interface. Nanostructured broadband and wide-angle AR structures have been developed using a scalable self-assembly process. Ultra-high performance of the nanostructured AR coatings has been demonstrated on various substrates such as quartz, sapphire, polymer, and other materials typically employed in optical lenses. AR coatings on polycarbonate lead to optical transmittance enhancement from approximately 90% to almost 100% for the entire visible, and part of the near-infrared (NIR), band. The AR coatings have also been demonstrated on curved surfaces. AR coatings on n-BK7 lenses enable ultra-high light transmittance for the entire visible, and most of the NIR, spectrum. Nanostructured oxide layers with step-graded index profiles, deposited onto the optical elements of an optical system, can significantly increase sensitivity, and hence improve the overall performance of the system.

The BiFeO3/BaTiO3 (BFO/BTO) multilayers were deposited on Pt/Ti/SiO2/Si substrates using sol-gel spin coating technique. The electric and magnetic studies on BFO/BTO multilayer structures were carried out for different number of layers. Enhancement in multiferroic properties were seen for all the prepared multilayers as compared to individual BTO and BFO thin films. Maximum value of ferroelectric polarization 71.18 µC/cm2 and saturation magnetization 69.85 emu/cm3 was obtained for multilayer structure having five layers. The observed enhancement in the multiferroic properties of the multilayer system is due to the increased interfacial stress and multiferroic coupling between the alternating layers.