Atomic Concentration Ratio Research Articles

Silicon oxide film formation by spraying tetraethyl orthosilicate onto substrate with simultaneous low-energy SiO+ ion-beam irradiation

We attempted to deposit silicon oxide films by spraying tetraethyl orthosilicate (TEOS) onto a substrate while the substrate was also irradiated with a low-energy SiO+ ion beam. The energy of the SiO+ ions was 55 eV, and the substrate temperature was 300 °C. Following this process, we were able to deposit a film on the substrate. X-ray photoelectron spectroscopy (XPS) measurements of the film showed that it was composed of silicon oxide. XPS analysis also showed that the oxygen-to-silicon atomic concentration ratio (O/Si ratio) for the film was 1.57. For comparison, an SiO+ ion beam was used to irradiate a substrate at room temperature with simultaneous spraying of TEOS. XPS analysis of the deposited film showed that it was silicon oxide with an O/Si ratio of 1.45. In this case, however, a relatively large number of carbon atoms (7 at. %) were incorporated into the film. In both the 300 °C and room-temperature cases, we confirmed that the film deposition rate was substantially improved by supplying TEOS during SiO+ ion-beam irradiation.

Extracting mechanical and microstructural properties of Cu–Zr thin film alloys by MEMS, AFM and ellipsometer

The quantification of the atomic concentration ratios of thin-film metallic alloys having low atomic ordering is challenging, particularly if they are grown on similar metals and possess different surface chemistries. Micromechanical and optical methods have been used to correlate the elemental ratios with the mechanical and optical properties of the films. The room-temperature growth of Cu–Zn thin-film alloys with varying elemental ratios on cosputtered Si substrates was performed to obtain an amorphous film structure. X-ray diffraction patterns confirmed that the grown films exhibited a very short range ordering, suggesting an amorphous structure. The mechanical properties of the films evaluated using microelectromechanical system (MEMS) indicated that the alloy films with moderate Zr concentrations had lower surface stress compared to those with low and high Zr concentrations. Furthermore, spectroscopic ellipsometry was employed to qualitatively assess the relaxation times of free carriers. The results demonstrated a strong correlation between the relaxation times and surface roughness measurements, showing that the microstructure and resistivity characteristics of the alloys align with the Nordheim semiempirical model. The extinction coefficient of the binary alloy film linearly depends on the metallic bulk concentration ratio in a specific metallic ratio range, paving the way for realizing qualitative elemental percentage assessment in the field of metrology.

Surface Modification and Mechanical Properties Improvement of Bamboo Fibers Using Dielectric Barrier Discharge Plasma Treatment.

The effect of argon (Ar) and oxygen (O2) gases as well as the treatment times on the properties of modified bamboo fibers using dielectric barrier discharge (DBD) plasma at generated power of 180 W were investigated. The plasma treatment of bamboo fibers with inert gases leads to the generation of ions and radicals on the fiber surface. Fourier transform-infrared spectroscopy (FTIR) confirmed that the functional groups of lignin and hemicellulose were reduced owing to the removal of the amorphous portion of the fibers by plasma etching. X-ray diffraction analysis (XRD) results in an increased crystallinity percentage. X-ray photoelectron spectroscopy (XPS) results showed the oxygen/carbon (O/C) atomic concentration ratio increased with increasing treatment time. The fiber weight loss percentage increased with increased treatment time. Scanning electron microscopy (SEM) images showed that partial etching of the fiber surface led to a higher surface roughness and area and that the Ar + O2 gas plasma treatment provided more surface etching than the Ar gas treatment because of the oxidation reaction of the O2 plasma. The mechanical properties of fiber-reinforced epoxy (FRE) matrix composites revealed that the F(tr)RE-Ar (30) samples showed a high tensile strength, whereas the mechanical properties of the F(tr)RE-Ar + O2 sample decreased with increased treatment time.

Effects of Polystyrene Diet on the Growth and Development of Tenebrio molitor.

In recent years, the role of Tenebrio molitor in degrading polystyrene foam through its gut microbes has become the focus of research. However, little literature has reported the effect of feeding on polystyrene foam on the growth and development of Tenebrio molitor. In this study, we investigated the impacts of different polystyrene by evaluating the vital signs of Tenebrio molitor fed in the intestines and excrement fluids using RNA-Seq t.echnology and then verifying the transcriptome sequencing findings using qRT-PCR technology. The average weight of Tenebrio molitor larvae in the wheat bran group increased significantly. Tenebrio molitor larvae in the PS group, on the other hand, didn’t grow as much and had a much lower average weight than those in the wheat bran group. Compared to the bran group, the excrement of Tenebrio molitor fed only on polystyrene foam was flaky and coarse, increased nitrogen and phosphorus atomic concentration ratios by about 50%, decreased potassium atomic concentration ratios by 63%, with the enterocytes and circular muscle of Tenebrio molitor falling as well. Kyoto Encyclopedia of Genes and Genomes enrichment indicated that the differential genes were mainly related to metabolic pathways. There was an agreement between qRT-PCR and RNA-Seq analyses for the growth and development genes chitinase, heat shock protein 70, and cytochrome P450. Only feeding polystyrene foam shall lead to the growth and development retardation of Tenebrio molitor.

Low-energy Ar+ ion beam induced chemical vapor deposition of silicon carbide films using dimethylsilane

In this paper, a methodology for silicon carbide (SiC) film formation by ion beam induced chemical vapor deposition (IBICVD) using dimethylsilane (DMS) is presented. Both pure DMS gas and Ar+ ion beam were simultaneously injected to a Si substrate. The Ar+ ion energy was 100 eV. The Si substrate temperature was 400, 600, or 800 °C. The duration of each ion beam injection experiment was 10 h. When the substrate temperature was 400 °C, no film formation occurred by the IBICVD experiment. In the case of 600 °C, a film was found to be formed on the substrate by the injection of both DMS gas and Ar+ ion beam. Although Fourier transform infrared (FTIR) spectroscopy measurement of the film showed that the film consisted of SiC, the film thickness was not enough to analyze the film characteristics further. When the Si substrate was set at 800 °C, a film was formed on the substrate by IBICVD. FTIR, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) measurements of the film showed the occurrence of SiC deposition. The XPS measurement also showed that the atomic concentration ratio of carbon to silicon (C/Si ratio) of the film was 1.36. Therefore, excessive C atoms were incorporated to the deposited films. On the contrary, the C/Si ratio of a SiC film prepared by the thermal CVD method using DMS was 1.88. These results suggest that the Ar+ ion beam induced chemical vapor deposition using DMS is useful for reducing of the amount of C atoms to be excessively included in the film.

Enhanced photonics devices based on low temperature plasma-deposited dichlorosilane-based ultra-silicon-rich nitride (Si8N)

Ultra-silicon-rich nitride with refractive indices ~ 3 possesses high nonlinear refractive index—100× higher than stoichiometric silicon nitride and presents absence of two-photon absorption, making it attractive to be used in nonlinear integrated optics at telecommunications wavelengths. Despite its excellent nonlinear properties, ultra-silicon-rich nitride photonics devices reported so far still have fairly low quality factors of sim 6times {10}^{4}, which could be mainly attributed by the material absorption bonds. Here, we report low temperature plasma-deposited dichlorosilane-based ultra-silicon-rich nitride (Si8N) with lower material absorption bonds, and ~ 2.5× higher quality factors compared to ultra-silicon-rich nitride conventionally prepared with silane-based chemistry. This material is found to be highly rich in silicon with refractive indices of ~ 3.12 at telecommunications wavelengths and atomic concentration ratio Si:N of ~ 8:1. The material morphology, surface roughness and binding energies are also investigated. Optically, the material absorption bonds are quantified and show an overall reduction. Ring resonators fabricated exhibit improved intrinsic quality factors sim 1.5times {10}^{5}, ~ 2.5× higher compared to conventional silane-based ultra-silicon-rich nitride films. This enhanced quality factor from plasma-deposited dichlorosilane-based ultra-silicon-rich nitride signifies better photonics device performance using these films. A pathway has been opened up for further improved device performance of ultra-silicon-rich nitride photonics devices at material level tailored by choice of different chemistries.

EFFECTS OF MODIFICATION WITH MELAMINE–UREA–FORMALDEHYDE RESIN ON THE PROPERTIES OF UREA PRETREATED EUCALYPTUS

Eucalyptus urophylla was treated with melamine-urea-formaldehyde resin (MUF) after pretreatment with urea solution. The properties of the wood were then determined.The weight percent gain (WPG) and, antiswelling efficiencies (ASE) of the wood treated with urea+MUF were 14% and, 45% higher than those of untreated wood, respectively. The water absorption (WA) of the wood treated with urea+MUF was decreased approximately 50% lower than that of the untreated wood. However, the mechanical properties of the wood treated with urea+MUF were weakened due to the destruction of the structure of wood. An X-ray photoelectron spectroscopy (XPS) analysis revealed that the atomic concentration ratio of O/C was increased. The ratio of C1 was decreased as the lignin and extractives contents were decreased, while theratios of C2 and C3 were increased. The urea solution pretreatment was conducive to theimpregnation of wood functional modifiers.

The effects of scandium heterogeneous distribution on the precipitation behavior of Al3(Sc, Zr) in aluminum alloys

Sc-containing Al alloys have excellent mechanical properties, which provide the foundation for their applications. The precipitation of the Al3Sc/Al3(Sc, Zr) is generally considered to be a key factor for the performance boost. However, the performances of the alloy in different production batches often exhibit unstable and fluctuation, which may be related to the heterogeneous of scandium. Herein, we investigated the precipitation behaviors of Al3Sc/Al3(Sc, Zr) phases in the Al-0.5Sc and Al-0.5Sc-0.25Zr alloys at 340 °C. Results shown that the high scandium‑zirconium ratio not only lead to the discontinuous precipitation, but also contribute to the abnormal continuous Al3(Sc, Zr) precipitation in Al-0.5Sc-0.25Zr alloy. The morphology of abnormal Al3(Sc, Zr) is similar to the common secondary Al3(Sc, Zr) phase with a coffee-bean like morphology. With the aid of Three-Dimensional Atomic Probe (3DAP), the core-shell structures of Al3(Sc, Zr) phases are quantitatively analyzed. In the shell layer of abnormal Al3(Sc, Zr) phase, the atomic concentration ratio of Sc to Zr is much higher than the common continuous precipitated Al3(Sc, Zr) phase. The abnormal Al3(Sc, Zr) phase may be one of the key factors for the structure heredity of Sc-containing Al alloys.

Reference XPS spectra of amino acids

In this report we present XPS data for five amino acids (AAs) (tryptophan, methionine, glutamine, glutamic acid, and arginine) with different side chain groups measured in solid state (powder form). The theoretically and experimentally obtained chemical structure of AAs are compared. Here, we analyse and discuss C 1 s, N 1 s, O 1s and S 2p core level binding energies, FWHMs, atomic concentrations of the functional groups in AAs. The experimentally obtained and theoretically calculated ratio of atomic concentrations are compared. The zwitterionic nature of methionine and glutamine in solid state was determined from protonated amino groups in N 1s peak and deprotonated carboxylic groups in the C 1s spectrum. The obtained XPS results for AAs well correspond with previously reported data.

Study of Mn doping on the Structural, Optoelectronic and Photoluminescence Properties of F-Doped SnO<sub>2</sub> Sprayed Thin Films for Optoelectronic Applications

The aim of this work is the production and the characterisation of (SnO2: (Mn, F)) thin films with appropriate optoelectronic properties required for application as ohmic contacts in photovoltaic application devices. Transparent conducting Manganese-fluorine co-doped tin oxide (SnO2: (Mn, F)) thin films have been deposited onto preheated glass substrates using the chemical spray pyrolysis (CSP) method. The ([Mn2+]/[Sn4+]) atomic concentration ratio (y) in the spray solution is varied between 0 and 8 at. %. The structural, the opto-electrical and the photoluminescence properties of these thin films have been studied. It is found that the deposited thin films are polycrystalline with a tetragonal crystal structure corresponding to SnO2 phase having a preferred orientation along the (200) plane. Transmission and reflection spectra reveal the presence of interference fringes indicating the thickness uniformity and the surface homogeneity of the deposited samples. Photoluminescence behaviour of Mn-F co-doped SnO2 thin films was also studied. Photoluminescence spectra reveal the presence of the defects like oxygen vacancies in the materials. In addition, The electrical resistivity, volume carrier concentration, surface carrier concentration and electrical mobility were determined from Hall Effect measurements and the following results were obtained: n-type conductivity in all the deposited thin films, a low resistivity of 1.50×10-4 Ω cm, and a high electrical mobility of 45.40 cm2 V-1 s-1 with Mn co-doping concentration equals to 7 at. %. These experimental results show that the electrical properties of these thin films where greatly improved making them suitable as ohmic contacts in photovoltaic applications devices.

Structural Features of ZnxMg1 – xWO4 Mixed Crystals

The structural features of a series of ZnxMg1–xWO4 mixed crystals (x = 0, 0.26, 0.41, 0.68, or 1) have been investigated using X-ray diffraction analysis and Raman spectroscopy; the luminescence properties of the grown crystals have also been studied. The dependence of the unit-cell volume on the substitution-cation concentration x is determined. It is shown that the geometric parameters of WO6 octahedra are independent of the ratio of Zn and Mg atomic concentrations in crystals. Consistency between the luminescence and structural properties of ZnxMg1–xWO4 crystals is established.

Quantitative analysis on the oxygen diffusion in pyramidal textured surfaces of silicon and copper via transmission electron microscopy

In the process of microelectronic device fabrication, the oxygen atom plays a double role. It oxidizes Si producing the SiO2 layer. Moreover, it oxidizes the metal electrodes causing failures and enters the semiconductor acting as an impurity recombination center. This phenomenon is closely related to the oxygen diffusion in the material surface. Although a textured material surface is frequently used, the oxygen diffusion inside this surface is rarely studied. Studies are available only for planar material surfaces. In this work, monocrystalline Si slices with a pyramidal textured surface and a series of Cu films, which were deposited onto this substrate, were thermally oxidized. The oxygen diffusion in such textured surfaces was quantitatively analyzed via transmission electron microscopy. The oxygen distribution and the variation in the oxygen:cation atomic concentration ratio as a function of the oxide thickness were obtained. Thus, suboxide diffusion layers of SiOx and CuOx were found for the surfaces. In addition, the oxidation rate of the textured material surface was significantly reduced due to its lower oxygen partial pressure when compared to a planar surface. These results can be used to control the oxide thickness, to resist the electrode oxidation, and to reduce the concentration of oxygen recombination centers when using a textured material surface for optoelectronic devices.

Effects of minor alloying with Ge and In on the interfacial microstructure between Zn–Sn solder alloy and Cu substrate

The interfacial reactions of Zn30Sn (ZS), Zn30Sn-1Ge (ZS-1Ge), and Zn30Sn–1In (ZS-1In) on the Cu substrate were investigated. After reflowing at 450 °C for 5 min, the ε-CuZn5 (scallop-type), γ-Cu5Zn8 (flat-type), and β’-CuZn (flat-type) intermetallic compounds (IMCs) formed at the interface between the solders and Cu substrate. Phase transformation from ε-CuZn5 and β’-CuZn to γ-Cu5Zn8 was observed with an increasing aging time at 150 °C. The growth of γ-Cu5Zn8 layer was accompanied by the decrease of ε-CuZn5 and β’-CuZn layers. After aging for 360 h. γ-Cu5Zn8 layer became the main IMC layer at the interface. The addition of Ge and In decreased the diffusion rate of Cu and Zn in the intermetallic layer (IML). The first-principles calculations indicated that the diffusion activation energy per unit length of Cu and Zn atoms crossing a specific diffusion channel was similar. Based on first-principles calculations, the atomic concentration ratios of Cu to Zn in the three Cu–Zn IMC phases were calculated via a simple model. When the atomic concentration ratio of Cu to Zn exceeded 0.528, ε-CuZn5 transformed into γ-Cu5Zn8, and when the ratio of Cu to Zn was less than 0.838,β’-CuZn transformed into γ-Cu5Zn8. In addition, the precipitation of Sn–Ge and Sn–In solid phase at the IML suppressed the IMC growth. Accordingly, the diffusivity of Cu on the IMC layer of ZS, ZS-1Ge and ZS-1In solders was calculated to be 5.8 × 10−7, 5.7 × 10−7 and 4.6 × 10−7 m2/s, respectively.

Confinement induced variation of composition ratio in amorphous silicon carbide thin films and effect in optical properties

Thickness dependency in the composition ratio of amorphous silicon carbide (SiC) thin films and its effect in optical properties are reported. SiC thin films (~ 20 nm to 450 nm range) with very low surface roughness (<1 nm) were grown using dual ion beam sputtered (DIBS) deposition technique. Thinnest SiC film (~ 20 nm) exhibited higher atomic concentration of silicon (Si) relative to that of carbon (C), with C:Si = 0.7, whereas carbon to silicon atomic concentration ratio (C:Si) was found to increase with increasing SiC film thickness, and reached 1:1 ratio for thickest SiC film (about 450 nm), using X-ray photoelectron spectroscopy (XPS) analysis. XPS was employed to investigate the chemical composition and bonding configuration of SiC. A thickness dependent distinct change in band gap as a consequence of variation in the composition ratio in SiC films, is reported, which indicates potential control on electrical and optical properties of the system.

Growth, Compositions, and Mechanical Characteristics of Sodium–Gadolinium Molybdate Single Crystals

A concentration series of sodium–gadolinium molybdate single crystals have been grown by the Czochralski method from melts of stoichiometric and some nonstoichiometric compositions in atmospheres with different oxygen contents. The actual compositions, microhardness, and crack resistance of the grown crystals have been investigated. All crystals are characterized by a significant sodium deficit with respect to stoichiometry and a large number of vacancies in the (Na + Gd) sublattice. The range of congruent melting is determined for this compound, and its homogeneity range is estimated to extend (on the scale of atomic concentration ratios Gd/Na) at least from 1.10 to 1.75. It is found that the microhardness of sodium– gadolinium molybdate crystals is significantly anisotropic, whereas the degree of crack resistance anisotropy does not exceed the measurement error. At the same time, neither microhardness nor crack resistance exhibit any significant dependence on the growth charge composition and the synthesis conditions in the investigated range of variation in these parameters.

Preparation of Sword-Type Leaf-Like Zirconium Oxide Films by Electrolysis

Zirconium oxide (ZrOx) films were successfully prepared on a transparent conducting substrate (fluorine-doped tin oxide) by galvanostatic cathodic electrolysis of a solution containing ammonium hexafluorozirconate (AFZ) and ammonium nitrate at 323 K. The morphology of the film evidently changed based on the initial concentration of AFZ in the solutions. The film prepared at comparably higher AFZ concentration exhibited aggregates of sword-type leaf-like units tens of micrometers in size in the longitudinal direction, radially growing and dividing into secondary structure. On the other hand, normal planar films of a micrometer order were deposited at a lower concentration of the AFZ solution. The films were classified as zirconium oxyfluorides (Zr–O–F) from the atomic concentration ratios of Zr, O, and F determined by X-ray fluorescent spectrometry analysis. Regardless of the initial AFZ concentrations, the crystallographic structures of the films were converted to monoclinic crystalline ZrO2 (baddeleyite) by the calcination at 773 K. The leaf shape of the film obtained in the solution of higher AFZ concentration was maintained following the calcination process, indicating the development of a 3D ZrO2 film. The present work evaluated the chemical character of the films and gave deeper insight into the growth mechanism of these remarkable materials.

Preparation of layer-reinforced nanocomposite based on polytetrafl uoroethylene by laser ablation and ion-plasma modifi cation

The results of researches devoted to solving the problem of obtaining of layered-reinforced nanocomposite based on polytetrafluoroethylene are presented. To ensure the required adhesive strength between the polymer base and the metal coating based on molybdenum, the surface layer of the base is reinforced with dispersed particles of zirconium dioxide. It is found that when reinforced with zirconium dioxide, the structure of polytetrafluoroethylene becomes more dense, and the ratio of atomic concentrations of fluorine and carbon in its composition decreases, which indicates decrease in the number of saturated fluorocarbon bonds in the polymer and leads to higher chemical activity of polytetrafluoroethylene. The obtained data on change in the chemical state of the layered-reinforced composite components indicate high degree of interaction between the polymer matrix elements, reinforcing components and coating elements in the area of the intermediate mesolayer.

First investigation of structural and optoelectronic properties of F and Ni co-doped SnO2 sprayed thin films

Transparent conducting Nickel-fluorine co-doped tin oxide (SnO2: (Ni, F)) thin films were synthesized chemically by spray pyrolysis technique (CSP) using various Ni concentrations onto hot glass substrates. The [Ni2+]/[Sn4+] atomic concentration ratio (y) in the spray solution was varying from 0 to 3 at. % by a step of 1 at. %. The y variation effect on the structural, optical and electrical properties was studied. It was found from the X-ray diffraction analysis that the films were polycrystalline with tetragonal structure corresponding to pure SnO2 phase having the (200) as preferred growth direction. The optical band gap energy increased from 3.71 to 3.88 eV with increasing the nickel doping concentration in the spray solution. Photoluminescence behaviour of Ni-F co-doped SnO2 thin films was also studied. In addition, electrical resistivity (ρ), volume carrier concentration (Nv), and Hall mobility (μ) were determined from Hall Effect measurements and it was found that all the elaborated thin films had n-type conductivity. The lowest resistivity of 3.16 × 10−5 Ω.cm, and highest Hall mobility of 10.07 × 105 cm2.V-1.s-1 were obtained at a Ni concentration of 3 at. %.

Optoelectronic Properties of Fluorine and Cobalt Co-Doped Tin Oxide Thin Films Deposited by Chemical Spray Pyrolysis

Transparent conducting Cobalt-fluorine co-doped tin oxide (SnO2: (Co, F)) thin filmswere deposited onto preheated glass substrates using the chemical spray pyrolysis method. The ([Co2+]/[Sn4+]) atomic concentration ratio (y)in the spray solution was varied between 0 and 5 at. %. The structural, electrical, optical and photoluminescence properties of these films were studied. It is found that the thin films are polycrystalline with a tetragonal crystal structure corresponding to SnO2 phase having a preferred orientation along the (200) plane. Transmission and reflection spectra reveal the presence of interference fringes indicating thickness uniformity and surface homogeneity of the deposited thin films. The electrical resistivity (ρ), volume carrier concentration density (Nv), surface carrier concentration density (Ns) and Hall mobility (μ) of the synthesized thin films were determined from the Hall Effect measurements in the Van der Paw-configuration and the following results were obtained: n-type conductivity in all deposited films, a low resistivity of 1.16×10-2 Ω.cm, and a high Hall mobility of 15.13×102 cm2.V-1.s-1with Co concentration equals to 3 at. %. These results show that the electrical properties of these thin films where greatly improved making them suitable as ohmic contact in photovoltaic application devices.

Development of the Physicochemical Properties of the GaSb(100) Surface in Ammonium Sulfide Solutions

Various conditions of passivation of the GaSb(100) surface by ammonium sulfide ((NH4)2S) solutions depending on the solution concentration, solvent, and treatment time are investigated by X-ray photoelectron spectroscopy and atomic-force microscopy. It is shown that treatment of the GaSb(100) surface by any (NH4)2S solution leads to removal of the native oxide layer from the semiconductor surface and the formation of a passivating layer consisting of various gallium and antimony sulfides and oxides. The surface with the lowest roughness (RMS = 0.85 nm) is formed after semiconductor treatment with 4% aqueous ammonium sulfide solution for 30 min. Herewith, the atomic concentration ratio Ga/Sb at the surface is ~2. It is also found that aqueous ammonium sulfide solutions do not react with elemental antimony incorporated into the native-oxide layer. The latter causes a leakage current and Fermi-level pinning at the GaSb(100) surface. However, a 4% (NH4)2S solution in isopropanol removes elemental antimony almost completely; herewith, the semiconductor surface remains stoichiometric if a treatment duration is up to 13 min.