Chemical Properties Of Thin Films Research Articles

Influence of annealing on the properties of chemically prepared SnS thin films

Thin films of SnS were deposited chemically, and they are annealed at four different temperatures: 100 °C, 150 °C, 200 °C, and 250 °C. X-ray diffraction, Raman analysis, UV-visible spectroscopy, field emission scanning electron microscopy, and energy dispersive spectroscopy were used to investigate the impact of annealing temperature on the structural, optical, morphological, and chemical properties of thin films. As the annealing temperature rose, it was seen from the XRD patterns that the crystallinity of SnS films improved. At 250 °C, the film was almost evaporated, and the XRD pattern showed no peaks at all. The lattice strain and crystallite size were computed from the WilliamsonHall plots. The crystallite size increased and the lattice strain decreased with the increase in the annealing temperature. According to optical investigations, the samples' optical bandgap shrank as the annealing temperature rose. Morphological studies showed the formation of well-adhered films, and as the annealing temperature increased, the film became denser and more continuous with larger grains. The atomic weight percentage of sulphur decreased as the annealing temperature increased, according to the EDS analysis. Photovoltaic structures with the configuration ITO/SnS/CdS/Ag were fabricated. From the I-V characteristics, it was observed that the cell structure formed with SnS annealed at 200 °C showed better cell performance.

A study on the optical, chemical and dielectric properties of PPCIN thin films derived from essential oil compounds using RF plasma polymerisation technique

Polymer-based nanostructured films were produced on various substrates using Radio Frequency (RF) plasma polymerization technique from Cinnamaldehyde monomer which is an organic compound. To fabricate polymer thin film, the pressure, the deposition time and RF power were set to 480 mTorr, 30 min and 15, 20 and 30 W, respectively. The effect of RF power on the optical, morphological and chemical properties of thin films were investigated. The optical, morphological and chemical properties were determined by UV–Vis spectroscopy, Atomic Force Microscopy (AFM) and FTIR spectroscopy, respectively. The average surface roughness of thin films was detected as 5.7 nm, 3.9 nm and 11.7 nm using AFM depending on the increase in RF power. Using FTIR spectroscopy, the chemical structure of the polymer thin films was compared with that of the monomer material, and it was found that the majority of the functional groups belonging to the monomers also appeared in the thin films. Optical band gap of thin films increased with RF power and these values were determined as 2.83 eV, 3.05 eV and 2.98 eV, respectively. The extinction coefficients and refractive indices of the thin films were measured at 500 nm between 0.00183–0.00522 and 2.40–2.78, respectively.

Phthalocyanines based QCM sensors for aromatic hydrocarbons monitoring: Role of metal atoms and substituents on response to toluene

The sensing properties of various metallophthalocyanines layered on Quartz Crystal Microbalance (QCM) transducers towards toluene vapor were investigated. Structural and morphological properties of thermally evaporated thin films of substituted and unsubstituted phthalocyanines were firstly characterized by Infrared spectroscopy, X-ray Diffraction and Scanning Electron Microscopy. The sensing characteristics were then determined from QCM responses to toluene at room temperature and correlated to physical and chemical properties of thin films. Effects of molecular composition of phthalocyanine, especially the nature of metal atom in the central cavity and peripheral grafted substituents, on sensor metrological characteristics were established. No significant effect because of change of the central metal atom (Cu, Zn, Fe, Co) in monomeric phthalocyanines was observed on toluene sensitivity. In contrast, strong effects of substituents particularly tert-butyl group at the periphery of the phthalocyanine ring on sensor response were highlighted. The sensing behavior of metallophthalocyanines towards toluene has been interpreted in correlation with the chemical nature of the materials (nature of metal atom and peripheral grafting groups), the physical properties of the sensitive films (structure, morphology and thickness) and the involved molecular interactions forces.

Optical Characterization of Amorphous Hydrogenated Carbon (a-C:H) Thin Films Prepared by Single RF Plasma Method

Methane (CH4) plasma was used to produce amorphous hydrogenated carbon (a-C:H) films by a single capacitively coupled radio frequency (RF) powered plasma system. The system consists of two parallel electrodes: the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy (OES). The structural and optical properties were analyzed via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.

Mimicry of sputtered i-ZnO thin films using chemical bath deposition for solution-processed solar cells.

Solution processing provides a versatile and inexpensive means to prepare functional materials with specifically designed properties. The current challenge is to mimic the structural, optical, and/or chemical properties of thin films fabricated by vacuum-based techniques using solution-based approaches. In this work we focus on ZnO to show that thin films grown using a simple, aqueous-based, chemical bath deposition (CBD) method can mimic the properties of sputtered coatings, provided that the kinetic and thermodynamic reaction parameters are carefully tuned. The role of these parameters toward growing highly oriented and dense ZnO thin films is fully elucidated through detailed microscopic and spectroscopic investigations. The prepared samples exhibit bulk-like optical properties, are intrinsic in their electronic characteristics, and possess negligible organic contaminants, especially when compared to ZnO layers deposited by sol-gel or from nanocrystal inks. The efficacy of our CBD-grown ZnO thin films is demonstrated through the effective replacement of sputtered ZnO buffer layers within high efficiency solution processed Cu2ZnSnS4xSe4(1-x) solar cells.

Chemical properties of hydroxyapatite deposited through electrophoretic process on different sandblasted samples

Abstract An implantable material based on titanium (Ti6Al4V) was sandblasted in order to be deposited with a thin film of hydroxyapatite. Two samples of the alloy, in a shape of a bar with 10 mm diameter and 20 mm length, were subjected to mechanical treatment. After deposition of the hydroxyapatite through electrophoresis process, the samples were analyzed by scanning electron microscopy. The nature and chemical properties of thin films formed on Ti-based substrate were investigated with electrochemical impedance spectroscopy based on the extremely high polarization resistance of the material. The results revealed the formation of a homogeneous layer on the surface of the metallic substrate. The layer composed of TiO2 and hydroxyapatite provided a high corrosion protection.

Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles

Functionally graded materials offer a way to improve the physical and chemical properties of thin films and coatings for different applications in the nanotechnology and biomedical fields. In this work, design and assembly of nanoporous tantalum films with a graded oxidation profile perpendicular to the substrate surface are reported. These nanoporous films are composed of size-selected, amorphous tantalum nanoparticles, deposited using a gas-aggregated magnetron sputtering system, and oxidized after coalescence, as samples evolve from mono- to multi-layered structures. Molecular dynamics computer simulations shed light on atomistic mechanisms of nanoparticle coalescence, which govern the films porosity. Aberration-corrected (S) TEM, GIXRD, AFM, SEM, and XPS were employed to study the morphology, phase and oxidation profiles of the tantalum nanoparticles, and the resultant films. Design and assembly of tantalum nanoparticle porous films with a graded oxidation profile perpendicular to the substrate surface were fabricated by magnetron-sputter inert-gas aggregation system. At the top-most layers of the film, the larger free-surface areas of nanoparticles enable the formation of thermodynamically stable Ta2O5.

Studies on the Controlling of the Microstructural and Morphological Properties of Al Doped ZnO Thin Films Prepared by Hydrothermal Method

Al doped ZnO (AZO) thin films were prepared on ZnO coated glass substrates by hydrothermal synthesis technique using aqueous solutions containing zinc nitrate hexahydrate, ammonium hydroxide, and different sodium citrate concentrations at 60 °C for 6 h. The effects of different trisodium citrate concentrations on the microstructural, crystallinity, morphological, optical, and chemical properties of thin films were investigated. X-ray diffraction studies showed that the AZO thin films were grown as a polycrystalline wurtzite hexagonal phase with a c-axis preferred orientation and without an unwanted second phase regardless of trisodium citrate concentrations. The thickness and grain sizes of AZO thin films decreased with increasing trisodium citrate concentration. The microstructure of AZO thin films was changed from flat to needle shaped and the morphology was smoother with increasing trisodium citrate concentrations. The AZO thin films have a high transmittance in the visible region ranging from 75 to 85% and a sharp edge from 366 to 374 nm.

CHARACTERISTICS OF THIN FILMS SYNTHESIZED FROM NANO BOEHMITE AND ORGANOALKOXYSILANE

We investigated the properties of inorganic–organic hybrid thin films prepared by sol–gel reaction. Sol solutions were synthesized by using two kinds of nanosized boehmite and methyltrimethoxysilane (MTMS) in variation with the amount of MTMS at different reaction times. Boehmite nano sol of spherical and fibrous shapes was used as inorganic material, and MTMS was used as organic material. The morphology of boehmite nano sol powder was observed by transmission electron microscopy. Coating sols were prepared from boehmite sol and MTMS by sol–gel reaction. Physical and chemical properties of thin films prepared from boehmite and MTMS sols were investigated. Surface hydrophobicity, roughness, thickness, thermal resistance and electrical resistivity of boehmite/MTMS thin films were investigated.

Correlation between mechanical, optical and chemical properties of thin films deposited by PECVD

Plasma-polymerized films of vinyltriethoxysilane were prepared by plasma-enhanced chemical vapor deposition using an RF (13.56 MHz) helical coupling plasma system operated in a pulsed regime. Thin films deposited under the same deposition conditions but with different thicknesses (9.5 nm–10.5 µm) were analyzed with respect to mechanical, optical, and chemical properties.All the films exhibited a layered structure. The overlayer at the film surface with a thickness (0.9–34 nm) dependent on the sample thickness was revealed by AFM, nanoindentation, and ellipsometry. A gradient behavior of the refractive index and the Young's modulus within the overlayer was related to the surface morphology of the films. A gradient interlayer at the substrate was also discussed.

Modification of mechanical and chemical properties of thin films by ion bombardment

Many process parameters of physical vapour deposition (PVD) procedures cannot be controlled and varied independently. This makes an understanding of mechanisms and accurate optimization of film properties difficult. One method of avoiding the interdependence of parameters is the replacement of an ion-delivering plasma by a directed ion beam. In this paper several experimental approaches of ion-beam-assisted deposition (IBAD) are described and experimental results obtained using different techniques are listed. A number of studies performed by our grou[ are presented in order to illustrate the influence of ion energy, ion to atom arrival ratio, angle of ion incidence and gas pressure on film properties. The modification of adhesion, stress, structure (texture), hardness and purity of films on metal and ceramic substrates is discussed within the framework of recent results of other scientists.

Grain Growth in Thin Films

in the average crystal orientation and can even result in epitaxial films. It is therefore not surprising that grain growth can profoundly affect the mechanical, electrical, and chemical properties of thin films. In this article the mechanisms and modes of grain growth in thin films will be reviewed. The focus will be on those factors that lead to the evolution of grain orientations as well as grain si zes. Spec ific attention will also be gi ven to those factors that allow control of microstructural evolution in thin films.

The role of thin films in integrated solid-state sensors

This paper reviews recent developments in integrated solid-state sensors, with emphasis on the important roles played by thin films in these device structures. Most such sensors employ transducers and custom interface circuits on a common substrate, with fabrication based on the processes associated with integrated circuits. Specific examples are used to illustrate the important electrical, mechanical, thermal, optical, and chemical properties of thin films in integrated sensors. Recently proposed undercut polysilicon film structures are discussed as an alternative to traditional bulk structures for measuring parameters such as pressure and flow. A multielectrode intracortical recording array under development for closed-loop neural prostheses is also described. This microprobe can be realized with high yields, with recording sites spaced as close as a few microns, and with substrate widths of less than 50 μm. A thin-film silicon thermal imager utilizes thin dielectric windows and polysilicon thermopiles to realize a broadband infrared detector which does not require cooling and which can be realized with effective element spacings less than 200 μm.

Control of Film Properties by rf-Sputtering Techniques

The versatility of rf sputtering and related processes often allows one to tailor the properties of thin films in ways not always available with other methods of film deposition. Effects that occur at the target, in the gas discharge, and at the substrate are reviewed in the context of their over-all effect on the physical and chemical properties of thin films. Special emphasis is placed on the effects of substrate temperature and the bombardment of substrates by various energetic species. Techniques involving controlled bombardment of substrates (deposition with rf-induced substrate bias) are considered in detail.