Hydrophobic properties of the ion beam deposited DLC films containing SiOx

Diamond like carbon (DLC) films received considerable interest due to outstanding mechanical and tribological properties as well as chemical inertness and hydrophobicity. That combination is particularly interesting for possible application of the DLC as anti-sticking layers in novel lithographic techniques such as nanoimprint lithography, because Si, quartz and Ni - the most often used materials for imprint stamp formation - have high surface energy and, as a result, bad anti-adhesive properties. In present study, SiO_x containing DLC thin films were synthesized from hexamethyldisiloxane vapor and hydrogen gas mixture by direct ion beam deposition. Anti-sticking properties of the grown DLC thin films were evaluated measuring surface contact angle with water. Chemical composition and structure of the deposited films were investigated by X-ray photoelectron spectroscopy and FTIR spectrometry. Morphology of the films was measured by atomic force microscopy. Effects of hexamethyldisiloxane flux on structure, anti-sticking properties and surface morphology of the SiO_x containing DLC thin films were defined.     

Ion beam synthesis of the diamond like carbon films for nanoimprint lithography applications

Ion beam deposited hydrogenated undoped as well as SiO_x (SiO_x + N₂, SiO_x + Ar) doped DLC thin films were deposited and evaluated as possible anti-adhesive layers for nanoimprint lithography. Film surface contact angle with water was investigated as a measure of the surface free energy and anti-sticking properties. Contact angle of the DLC films was independent of SiO_x doping and ion beam energy. Air-annealing resistance in terms of the contact angle with water of the synthesized diamond like carbon films was investigated. Optical transmittance spectra of the DLC films in UV-VIS range were measured to investigate it as possible anti-sticking layers for UV imprint lithography applications. DLC films with the most promising combination of the UV absorption and anti-sticking properties were revealed. Preliminary imprint tests with uncoated and thin DLC film coated hot imprint stamps were performed.     

Structural and photocatalytic properties of TiO2/SiOx/TiOx multi-layer prepared by electron-beam evaporation method

TiO₂/SiO_x/TiO_x multi-layers on quartz glass were prepared by electron-beam evaporation method and their structural and photocatalytic properties were investigated. The photocatalytic activity of the TiO₂/SiO_x/TiO_x multi-layer was evaluated by the photodecomposition of methylene blue in aqueous solution. As the thickness of the SiO_x inter-layer increased, the surface roughness of the TiO₂/SiO_x/TiO_x multi-layer increased but the anatase crystallite size decreased. The TiO₂/SiO_x(80 nm)/TiO_x multi-layer exhibited excellent photocatalytic activity resulting from higher surface roughness and more trap levels in the SiO_x(80 nm) inter-layer.     

Dependence of Zr content on electrical properties of Bi3.15Nd0.85Ti3-xZrxO12 thin films synthesized by chemical solution deposition (CSD)

The Bi_3.15Nd_0.85Ti_3-xZr_xO₁₂ (BNTZ) thin films with Zr content (x = 0, 0.05, 0. 1, 0.15, and 0.2) were prepared on Pt/Ti/SiO₂/Si (100) substrates by chemical solution deposition (CSD) technique. The crystal structures of BNTZ films were analyzed by X-ray diffraction (XRD). The effects of Zr contents on the ferroelectric, dielectric properties, and leakage current of BNTZ films were thoroughly investigated. The XRD results demonstrated that all the films possessed a single phase bismuth-layered structure and exhibited the highly preferred (117) orientation. Among these films, the film with Zr content x = 0.1 held the maximum remanent polarization (2P_r) of 50.21 μC/cm² and a low coercive field (2E_c) of 210 kV/cm.     

Investigation of SiOxCy film as the encapsulation layer for full transparent OLED using hollow cathode discharge plasma at room temperature

The plasma polymer of SiO_xC_y film has attracted much attention because it could possess both the organic and inorganic properties simultaneously for wide range applications. In this work, a SiO_xC_y film with a gradient composition through tuning the N₂O/N₂O + Ar ratio from 0% to 100% was used for TOLED encapsulation using hollow cathode discharge plasma. In order to confirm whether the plasma damage was caused during the PECVD process, a ZnO buffer layer prepared using RF sputtering was deposited before encapsulation. Furthermore, the reference samples with glass lid encapsulation were also used for comparison. The results showed that the SiO_xC_y film with a gradient composition cooperated with the sputtering ZnO buffer layer was a simple and effective method for TOLED encapsulation.     

Multilayer amorphous hydrogenated carbon (a-C:H) and SiOx doped a-C:H films for optical applications

In this study SiO_x doped amorphous hydrogenated carbon (a-C:H) films were formed from hexamethyldisiloxane (with hydrogen transport gas) by closed drift ion beam deposition applying variable ion beam energy (300-800 eV). The band gap dependence on the deposition energy was determined and used in production of SiO_x doped a-C:H and a-C:H (formed from acetylene gas) multilayer (two and four layers) stack. Optical properties of the multilayer structures as well as individual layers were analysed in the UV-VIS-NIR range (200-1000 nm). It was shown that employing double or four layer systems, the reflectivity of the multilayer structure-crystalline silicon can be tuned to almost 0% at specific wavelength range (550-950 nm), important in solar cell applications.     

Mechanical and environmental properties of Ge1−xCx thin film

Ge_1−xC_x thin film was prepared by plasma-enhanced chemical vapor deposition (PECVD) using GeH₄ and CH₄ as precursors and its mechanical and environmental properties were investigated. The samples were measured by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectrum, FT-IR spectrometer, WS-92 testing apparatus of adhesion and FY-03E testing apparatus of salt and fog. The results show that the infrared refractive index of Ge_1−xC_x thin film varies from 2 to 4 with different x values. The adhesion increases with increasing gas flow ratio of GeH₄/CH₄ and decreases with increasing film thickness. The nanoindentation hardness number decreases with increasing germanium content. Three series films exhibit the best anti-corrosion property when the RF power is about 80 W, or substrate temperature is about 150 °C, or DC bias is about −100 V. Furthermore, increasing the gas flow ratio of GeH₄/CH₄ improves the anti-corrosion property of these films.     

MgxZn1−xO (x = 0-1) films fabricated by sol-gel spin coating

Mg_xZn_1−xO films were deposited onto the glass substrate by a sol-gel spin coating method. The drying and annealing temperatures were 300 and 500 °C in air. As x varies from 0 to 1, it was observed that the crystal structure is changed from wurtzite ZnO to cubic MgO. The morphology characterizations of these films were observed by scanning electron microscope. The randomly oriented hexagonal nanorods were gown on the glass surface when x = 0 and 0.25, which became disappeared with increasing Mg contents. The optical properties of these films were investigated by room-temperature photoluminescence (PL) and UV-vis absorption spectra, which show that the optical band gap and photoluminescence in the visible and UV regions can be ideally tuned by varying the Mg contents in the Mg_xZn_1−xO alloy films.     

Growth and properties of the ion beam deposited SiOx containing DLC films

In the present study SiO_x containing diamond-like carbon (DLC) films were synthesized by the closed drift ion source from hexamethyldisiloxane vapor. Kinetics of the growth of DLC films was investigated using optical emission spectroscopy (OES). Structure, chemical composition, electrical and optical properties of the synthesized films were studied. The effects of ion beam energy were investigated. The main atomic hydrogen Balmer series lines and the intense broad CH group related peak were detected in the OES spectra registered in-situ during SiO_x containing diamond-like carbon film synthesis. The intensity ratio of H-β/CH peaks increased with the increase of applied ion beam energy. It was explained by activation of the dissociation of the hexamethyldisiloxane molecules. Changes of the structure of the diamond-like carbon films were observed for the films deposited under intense dissociation conditions.     

Composite SiOx/fluorocarbon plasma polymer films prepared by r.f. magnetron sputtering of SiO2 and PTFE

Composite films SiO_x/fluorocarbon plasma polymers were prepared by r.f. sputtering from two balanced magnetrons equipped with polytetrafluoroethylene (PTFE) and silica (SiO₂) targets. Argon was used as the working gas. The obtained films were characterised by means of XPS, RBS, FTIR, AFM, TEM, microhardness and static contact angle measurements. The obtained SiO_x/fluorocarbon plasma polymer films reveal different wettability (static contact angle of water ranges from 68° to 40°) and hardness (ranges from 720 to 3200 N/mm²) when the volume fraction ratio (filling factor) of SiO₂ changes from 0.01 to 0.7. The concentration of elements determined by RBS/ERDA varies strongly over this range of filling factors. The heterogeneous structure of the composite films is indicated by TEM at high SiO_x contents.     

The properties of transparent semiconductor Zn1 − xTixO thin films prepared by the sol-gel method

Transparent semiconductor thin films of Zn_1 − xTi_xO (0 ≦ x ≦ 0.12) were deposited on alkali-free glass substrates by the sol-gel method. The effects of Ti addition on the crystallization, microstructure, optical properties and resistivity of ZnO thin films were investigated. The as-coated films were preheated at 300 °C, and then annealed at 500 °C in air ambiance. X-ray diffraction results showed all polycrystalline Zn_1 − xTi_xO thin films with preferred orientation along the (002) plane. Ti incorporated within the ZnO thin films not only decreased surface roughness but also increased optical transmittance and electrical resistivity. In the present study, the Zn_0.88Ti_0.12O film exhibited the best properties, namely an average transmittance of 91.0% (an increase of ~ 12% over the pure ZnO film) and an RMS roughness value of 1.04 nm.     

Electrode effect on resistive switching of Ti-added amorphous SiOx films

Ti-added amorphous SiO_x films were sputter-deposited into stacks of Pt/SiO_x/Pt and Cu/SiO_x/Pt. Optimally prepared Pt/SiO_x/Pt exhibits unipolar resistive switching over 10² cycles, resistance ratio ∼ 10³, yet wide voltage distribution (2 ∼ 7 V for SET, 0.5 ∼ 1.5 V for RESET). Cu/SiO_x/Pt exhibit similar endurance, resistance ratio up to 10⁷, and SET and RESET voltages reduced to 1.8 ∼ 4.2 V and 0.5 ∼ 1 V, respectively. Cu diffusion into SiO_x at the virgin state may play a role in resistive switching of Cu/SiO_x/Pt stack besides of filament conduction. Ti-added amorphous SiO_x films incorporating Cu electrode shows potential for resistive memory.     

Structural study of Si1 − xGex nanocrystals embedded in SiO2 films

We have investigated the structural properties of Si_1 − xGe_x nanocrystals formed in an amorphous SiO₂ matrix by magnetron sputtering deposition. The influence of deposition parameters on nanocrystal size, shape, arrangement and internal structure was examined by X-ray diffraction, Raman spectroscopy, grazing incidence small angle X-ray scattering, and high resolution transmission electron microscopy. We found conditions for the formation of spherical Si_1 − xGe_x nanocrystals with average sizes between 3 and 13 nm, uniformly distributed in the matrix. In addition we have shown the influence of deposition parameters on average nanocrystal size and Ge content x.     

Chemical bonding of a-Ge1−xCx:H films grown by RF reactive sputtering

Amorphous hydrogenated germanium-carbon (a-Ge_1−xC_x:H) films were deposited by RF reactive sputtering pure Ge (1 1 1) target at different flow rate ratios of CH₄/(CH₄+Ar) in a discharge Ar/CH₄, and their composition and chemical bonding were investigated using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). XPS and FTIR results showed the content of germanium in the films decreased with the increase of the flow rate ratio CH₄/(Ar+CH₄), and the Ge-C, Ge-H, C-H bonds were formed in the films. The fraction of Ge-C, Ge-H, and C-H bonds was strongly dependent on the flow rate ratio. Raman results indicated that the films also contain both Ge-Ge and C-C bonding. Based on the change of the chemical bonding of a-Ge_1−xC_x:H films with the flow rate ratio CH₄/(CH₄+Ar), an optimal experimental condition for the application of infrared windows was obtained.     

The influence of ambient conditions on properties of MgxZn1−xO films by sputtering

The Mg_xZn_1−xO films were prepared in different Ar-O₂ mixture ambience by magnetron sputtering. According to the X-ray diffraction (XRD) patterns and the energy dispersive X-ray spectroscopy (EDS) results, it was found that the Mg contents in the films varied with the different ratios of O₂/O₂+Ar, and the crystal quality of the films improved with the increasing of Mg contents. Meanwhile, the ultraviolet and visible (UV-vis) absorption spectroscopy indicated that the band gap of the films also increased. Moreover, it could be seen that the photoluminescence (PL) spectrum was different from that of undoped Zinc oxide (ZnO) films or the results in other reports on the Mg_xZn_1−xO films: there was no blueshift effect happening for the near-band-edge (NBE) emission in Mg_xZn_1−xO films with different Mg contents.     

Effect of thermal treatments on the structure of MoNxOy thin films

MoN_xO_y films were deposited on steel substrates by dc reactive magnetron sputtering. The depositions were carried out from a pure molybdenum target, varying the flow rate of reactive gases. X-ray diffraction (XRD) results revealed the occurrence of cubic MoN_x and hexagonal (δ-MoN) phases for the films with high nitrogen flow rates. The increase of oxygen content induces the decrease of the grain size of the molybdenum nitride crystallites. The thermal stability of a set of samples was studied in vacuum, for an annealing time of 1 h, for temperatures ranging from 500 to 800 °C in 100 °C steps. The results showed that pure molybdenum nitride films changed their structure from a meta-stable cubic MoN to hexagonal δ-MoN and cubic γ-Mo₂N-type structures with increasing annealing temperatures. The samples with molybdenum nitride films evidenced a good thermal stability, but those with molybdenum oxynitride coatings showed a tendency to detach with the increase of the annealing temperature.     

The deposition and optical properties of Ge1−xCx thin film and infrared multilayer antireflection coatings

The effects of deposition parameters on the deposition rate, microstructure, and composition of Ge_1−xC_x thin films prepared by plasma enhanced chemical vapor deposition were studied and the films' infrared optical properties were investigated. The results show that the carbon content of these films increases as the precursor gas flow ratio of CH₄:GeH₄ increases, while the infrared refractive index of these films decreases from 4 to 2. The deposition rate increases with the radio-frequency power and reaches a constant value when the power goes above 60 W. Ge_1−xC_x/diamond-like carbon infrared antireflection coatings were prepared, and the transmittance of the coatings in the band of 8 to 14 μm was 88%, which is superior to that of Zinc Sulfide substrate by 14%.     

Optical and electrical properties of TiOx thin films deposited by electron beam evaporation

The TiO_x thin films were prepared by electron beam evaporation using TiO as the starting material. The effect of the annealing temperature on the optical and electrical properties was investigated. The spectra of X-ray photoelectron spectroscopy reveal that Ti in the films mainly exist in the forms of Ti²⁺ and Ti³⁺ below 400 °C 24 h annealing. The charge transfer between different titanium ion contribute greatly to the color, absorption, and electrical resistance of the films.     

Enhanced ferromagnetic properties of multiferroic BiCoxFe1 − xO3 synthesized by hydrothermal method

The BiCo_xFe_1 − xO₃ samples have been successfully synthesized by hydrothermal process. The resulting products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDS), differential thermal analysis (DTA), and physical property measurement system (PPMS).It was found that the magnetization of the obtained products was greatly enhanced by Co substituting for Fe ions. Furthermore, the value of magnetism of BiCo_xFe_1 − xO₃ samples can be adjusted by Fe doping concentration. DTA curve indicates the ferroelectric properties of the obtained BCFO samples are not affected by Co substitution. Therefore, it would be interesting to realize thin films with similar compositions and study their properties in the interest of device applications.     

A study of atomic layer deposited LiAlxOy films on Mg-Li alloys

LiAl_xO_y films with thicknesses of 65-200 nm were deposited by the atomic layer deposition (ALD) technique on the LZ101 Mg-Li alloy. The ALD-deposited LiAl_xO_y films exhibit an amorphous structure and have an atomic ratios of Li:Al:O = 1:1:2. The potentio-dynamic polarization tests show that the corrosion resistance of Mg-Li alloys can be significantly improved due to the dense and pinhole-free structure as well as the excellent coverage and conformity of the ALD-deposited LiAl_xO_y films.