Narrow Results

Using the successive ionic layer adsorption and reaction (SILAR) method, we successfully deposited thin films (TFs) of both pure cadmium oxide (CdO) and strontium (Sr) CdO onto glass slides. Analysis of the films’ structure and morphology, conducted via field emission scanning electron microscopy and X-ray diffraction, revealed a polycrystalline cubic structure with porous nanoflake agglomerates. Further characterization involved ultraviolet–visible spectroscopy and photoluminescence spectrum measurements to explore the optical attributes of the CdO films. Notably, we observed significant impacts of Sr doping on both optical transmittance and photoluminescence emission intensity in the CdO nanostructures. Electrical measurements, carried out using four-probe Iviumstat analysis, demonstrated variations in resistivity with different levels of Sr doping. These findings highlight the potential for controlling specific physical features of CdO through Sr doping, making it a promising candidate for various device applications.

Fe₂O₃ thin films were deposited on alumina substrates by using the physical vapor deposition technique “RF magnetron sputtering”. The impact of the thermal treatment on the structural, optical and morphological properties was systematically investigated. The results of the structural characterizations reveal that the elaborated thin films present a main peak whichcorresponds to the crystalline plane (104) of the hematite ($\alpha$-Fe₂O₃). Furthermore, the Raman spectra confirm the existence of the hematite phase of the iron oxide. UV-Visible spectrophotometer analysis of Fe₂O₃ thin films before and after annealing shows that the transmittance increases with heat treatment. Moreover, the heat treatment at 500^∘C significantly improves the absorption coefficient $\alpha$, extinction coefficient k, refractive index n, and the band gap of Fe₂O₃ thin films. Furthermore, a spinel polarization change was found to be responsible for the ferrobehavior of Fe₂O₃ thanks to the lattice crystallinity enhancement. The density functional theory calculations demonstrate that the magnetic properties are very sensible to any induced strain in the Fe₂O₃ lattices.

In this study, we synthesized Co₃O₄ thin films using a sol–gel spin coating method and investigated the effect of heat treatment on their carbon dioxide (CO₂) gas sensing properties. To optimize their crystallinity and enhance their CO₂ sensitivity, the thin films were annealed at temperatures ranging from 400^∘C to 550^∘C. We characterized the morphological, structural, electrical, and optical properties of the Co₃O₄ thin films to gain insights into their behavior in the low operating temperature range (OTR). Our X-ray diffraction (XRD) analysis revealed that all the thin films exhibited a cubic structure, with improved crystallinity observed at higher annealing temperatures. We observed a decrease in band edges in the optical transmittance spectra of the thin films as the annealing temperature increased, indicating a redshift in the absorption edge. Notably, the highest electrical conductivity was observed for the sample annealed at 550^∘C, suggesting enhanced crystallinity and improved CO₂ gas sensitivity. These findings provide valuable insights into the optimization of Co₃O₄ thin films for CO₂ gas sensing applications.

The chemical bath deposition method (CBD) was used to create thin films of calcium zirconate on a glass substrate. After that, the samples were annealed for an hour at three different temperatures: $100^{\circ }$C, $200^{\circ }$C, and $300^{\circ }$C. The structural parameters of the samples like lattice strain, dislocation density and crystallite size were calculated from XRD analysis. The lattice strain was found to be very low. The crystallite size confirms the nano-size of the synthesized sample. From UV analysis, the optical energy direct bandgap was calculated in the range of 3.98–4.16eV. A higher annealing temperature of $300^{\circ }$C causes the thin film’s bandgap to diminish, confirming the calcium zirconate thin film’s broad bandgap characteristics. From SEM analysis, morphology, and adhesive nature was analyzed, and from AFM analysis, the grain size of the sample was found to be in 300nm.

The nature of oxide phases at metal–oxide interfaces, i.e. of oxide layers in the proximity of a metal surface, is assessed by critically examining the available data in the literature. The data reveal a trend towards the formation of reduced oxide phases with lower oxidation states in the vicinity of the interface with a metal. The physical origin of these interface-stabilized oxide layers is discussed and the possible causes include strong metal–metal bonding, high oxygen affinity of the substrate metal, reduction of the interfacial strain, and the stability of two-dimensional oxide phases.

We have carried out the calculations of vibrational dynamics in the low-dimensional structure with dimensions on the nanometer scale by using the matching formalism. The nanostructure model consists in the surface step produced at a perpendicular interface between two truncated thin films with different thickness. The theoretical approach determines the vibrational field in the direction where the translation symmetry is broken. The calculation concerns in particular the phonon dispersion curves localized on the interface and step edge, and employs the matching procedure in the harmonic approximation. The nearest and next nearest neighbors elastic force constants between the mass sites in the model, as well as a modification of the elastic strain field induced by the presence of the step, are considered. Analytic expressions are obtained for the phonon dispersion relations of the localized surface and edge elastic waves and the bulk phonons near a step. The breakdown of translational symmetry perpendicular to the step edge gives rise to several Raleigh-like branches localized in the neighborhood of step and interface. The effects of varying the elastic force constants at an interface and the strain field parameter near the step are studied. These factors influence the number of localized modes as well as their frequency, intensity and attenuation.

A thin-film bilayer structure consisting of polycrystalline Pb_0.85Sm_0.1TiO₃ and preferentially (111)-oriented Bi₂Ti₂O7 were prepared using the chemical solution deposition technique. Thin films were deposited by spin-coating. The structural properties of the films were examined by X-ray diffraction. The surface morphology and quality were studied by using an atomic force microscope. The films exhibit a good insulating property and resistance to breakdown. The clockwise hysteresis curve is referred to as polarization type switching, and the memory window is about 3.5 V. The accumulation capacitance and dielectric loss decrease with the increased annealing temperature. The (Pb, Sm)TiO₃/Bi₂Ti₂O₇ films in the "on" and "off" states are relatively stable.

Neodymium-doped Bi₄Ti₃O₁₂ (Bi_3.15Nd_0.85Ti₃O₁₂) thin films have been synthesized by metalorganic solution decomposition and deposited on SiO₂/p-Si(111) substrate by spin coating. The structural characteristic and crystallization of the films were examined by X-ray diffraction and atomic force microscope. The insulating property, dielectric constant and dissipation loss were found to be dependent on the annealing temperature. Nonhysteretic C–V curves at various frequencies were also collected. The films in the ON and OFF states were relatively stable.

Ag thin films deposited on Ru (0001) surface by molecular beam epitaxy, at temperatures of 20°C and 450°C, have been investigated using reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. For both growth temperatures, the in situ RHEED patterns of the Ag films exhibited an in-plane six-fold symmetry, indicating that the Ag deposit is in epitaxy with the Ru buffer surface. At RT, the RHEED technique indicated a three-dimensional growth (3D), while a layer-by-layer growth (2D) takes place at HT. The AFM images showed a granular structure of the surface of the deposited Ag layers with a large variation of the roughness with the growth temperature. XRD analysis gave indication of a strongly textured thin film along the growth direction. The lattice mismatch between the Ag and Ru is at the origin of a stress at the interface and defects structure in the film.

Lead-free Bi_0.5(Na_0.4K_0.6)_0.5TiO₃ films have been synthesized by a chemical solution deposition method and deposited on p-Si(111) substrate by spin coating. Powder of the precursor solution heated at 650°C was studied by infrared scattering spectroscopy. The structural characteristics and crystallization of the films were examined by X-ray diffraction. The surface morphology and quality were studied using atomic force microscopy. The films exhibit good insulating properties and resistance to breakdown. The clockwise hysteresis curve is referred to as polarization type switching and the memory window is about 1.5 V.

A simple method for determination of optical constants and thickness of semitransparent thin films deposited onto a transparent finite substrate has been developed. The method is based on the analysis of successive interference fringes of transmission spectra created by the films. It is essentially not necessary to obtain the envelope of transmission spectra in this method. The determined values of optical parameters are in good agreement with their true values used to generate transmission data. The accuracy of method in determining refractive index and thickness of the films is better than 1%.

It is known that in the condition of chemical vapor deposition (CVD) diamond process, molybdenum is capable of forming carbide known as the "glue" which promotes growth of the CVD diamond, and aids its adhesion by (partial) relief of stresses at the interface. Furthermore, the WC grains are reaction bonded to the Mo₂C phase. Therefore, molybdenum is a good candidate material for the intermediate layer between WC–Co substrates and diamond coatings. A molybdenum intermediate layer of 1–3 μm thickness was magnetron sputter-deposited on WC/Co alloy prior to the deposition of diamond coatings. Diamond films were deposited by hot filament chemical vapor deposition (HFCVD). The chemical quality, morphology, and crystal structure of the molybdenum intermediate layer and the diamond coatings were characterized by means of SEM, EDX, XRD and Raman spectroscopy. It was found that the continuous Mo intermediate layer emerged in spherical shapes and had grain sizes of 0.5–1.5 μm after 30 min sputter deposition. The diamond grain growth rate was slightly slower as compared with that of uncoated Mo layer on the WC–Co substrate. The morphologies of the diamond films on the WC–Co substrate varied with the amount of Mo and Co on the substrate. The Mo intermediate layer was effective to act as a buffer layer for both Co diffusion and diamond growth.

Thin films of Al₂O₃ were prepared by the sol–gel process. Dip-coating technique was used for deposition of the Al₂O₃ thin films onto glass substrates. Optical and structural properties of the films were investigated with respect to the annealing temperature (100–500°C). The structure of these films was determined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed for the analysis of surface morphology. For determination of the optical constants of Al₂O₃ thin films, UV-Visible spectrophotometry measurements were carried out. Annealing temperature affects the structural and optical properties of the Al₂O₃ thin films. The refractive index and extinction coefficient of the films at 550 nm wavelength increase from 1.56 to 1.66, and from 3.41 × 10^-5 to 5.54 × 10^-5, respectively while optical band gap and thickness of the films decrease from 4.15 eV to 4.11 eV, and 360 nm to 260 nm, respectively, by increasing annealing temperature from 100°C to 500°C.

We have investigated the effect of Bi on the heteroepitaxial growth of Co on Cu by reflection high-energy electron diffraction (RHEED) measurements. It was found that Bi enhanced the layer-by-layer growth of Co on the Cu(111) surfaces at 100°C. The dependence of the growth on Bi layer thickness suggested that there existed a suitable amount of Bi surfactant layer that enhanced smoother layered growth. On the contrary, for the case of Co growth on Cu(100), Bi depressed the layer-by-layer growth of Co on Cu(100). The surface segregation effect of Bi was also studied by Auger electron spectroscopy (AES).

Thin films of single c-domain/single crystal (PbMg_1/3Nb_2/3O₃)_1-x(PbTiO₃)_x, x = 0–0.4 (PMNT) were heteroepitaxially grown on (001)SrTiO₃ and (001)MgO substrates by magnetron sputtering using a quenching process. The lattice parameters of the quenched PMNT thin films were almost the same to the bulk values independently to the lattice parameters of substrates. The quenched PMNT thin films showed stress free structural properties, although the crystal structure of thin films is modified from bulk PMNT. The electromechanical properties are the same to the bulk single c-domain single crystals.

Pulsed laser deposition (PLD) is being investigated as an alternative technique to prepare hydroxyapatite coatings. In this research we studied the microstructure and phase composition of the PLD hydroxyapatite films. The surface morphology of the films is composed of droplets for which size ranges from hundreds of nanometers to a few micrometers. The cross-sectional morphology of the films shows that the films adhere to the substrate well and there are no microcracks, pores and other defects between substrate and films. The X-ray diffractometer results show that the deposited films are amorphous and the post heat treatment films consists of crystalline HA and TiO₂.

Indium tin oxide (ITO) thin films were prepared by radio frequency (RF) magnetron sputtering and under a quite low vacuum level of 2.3 × 10^-3Pa. The sputtering was done in an Ar and O₂ gas mixture at a temperature of 200°C. A ceramic In₂O₃:SnO₂ target (10 wt% SnO₂) was used. The microstructures of the films were investigated by a field emission scanning electron microscope (FESEM) and an X-ray diffractometer (XRD). X-ray photoelectron spectroscopy (XPS) was performed to characterize the composition of the films. ITO films with a high transparency in the visible wavelength range (80–95%) were obtained. The dependency of the electrical, optical and structural properties of ITO films on both the O₂ flow ratio (O₂/(O₂ + Ar)) and the working pressure was investigated. In the case of low working pressure (1 Pa), the more highly transparent and conducting films were produced at the lower O₂ flow ratio. High working pressure (2 Pa) gave rise to low quality, low transparency and amorphous films. Under RF sputtering at low vacuum level, the main contribution to the chamber atmosphere is due to water vapor. Oxygen originating from water vapor dissociation induced by plasma plays the same role as an oxygen or water vapor flux usually intentionally introduced in the system in order to have good quality films.

The rapid thermal annealing (RTA) process was adapted to crystallize the amorphous (Ba,Sr)TiO₃ thin films prepared on Si(111) substrates by RF magnetic sputtering deposition. The effect of annealing temperature, heating rate and duration time on crystallization was studied through X-ray diffraction and atomic force microscopy. The result shows that the crystallinity and grain size were strongly dependent on the temperature, heating rate, and duration time. Higher heating rate leads to smaller grain size. In high heating rate, the grain size shows different dependence of temperature from that of low heating rate. For a heating rate of 50°C/s, the grain size decreased with temperature increasing below 700°C, while after that temperature, the grain size increased slightly with the temperature increasing. At a certain temperature, the crystallinity and surface roughness improved with increase in annealing time, while grain size changed little. The effect of rapid heating rate on the nucleation and grain growth has been discussed, which contributes to the limited grain size of the annealed (Ba,Sr)TiO₃ thin films.

Crack-free Sm-doped Bi₂Ti₂O₇(Sm:Bi₂Ti₂O₇) thin films with a strong (111) orientation have been prepared on p-Si(111) by chemical solution deposition (CSD). The structural properties and crystallizations were studied by X-ray diffraction. The surface morphology and quality were examined using atomic force microscopy (AFM). The dielectric constant and loss factor at different frequencies were also evaluated at room temperature. Their insulation was studied, too. The films exhibit better insulating property than does the pure Bi₂Ti₂O₇.

In the present work, a novel DC glow discharge source with configurations of hollow cathode electrodes had been developed. Discharge properties of the plasma source had been characterized. Experimental data indicated that the discharge current of the plasma source increased with the discharge voltage. The phase change of the discharge was observed with the increase of gas pressures. After characterization, the hollow cathode electrodes was used to sputtering deposition of both carbon and carbon nitride films.

All samples were characterized by using Raman scattering spectroscopy. Typical D- and G-bands in the Raman spectrum of the samples were identified. In the case of carbon nitride films, the intensity ratio of D- and G-bands changed greatly with the deposition period of time. The shifts of D- and G-ands were also observed. In the case of carbon films, the intensity ratio of D- and G-bands slightly increased with an increase of the helium gas pressure from 100 to 200 Pa. The peak positions of the bands remained nearly unchanged with the variation of the helium gas pressure.