Precursor evolution and growth mechanism of BTO/YBCO films by TFA–MOD process

In this study, BaTiO3 （BTO）-doped YBCO films are prepared on LaA103 （100） single-crystal substrates by metal- organic decomposition （MOD） using trifluoroacetate （TFA） precursor solutions. The critical current density （Jc） of BTO/YBCO film is as high as 10 MA/cm2 （77 K, 0 T）. The BTO peak is found in the X-ray diffraction （XRD） pattern of a final YBCO superconductivity film. Moreover, a comprehensive study of the precursor evolution is conducted mainly by X-ray analysis and μ-Raman spectroscopy. It is found that the TFA begins to decompose at the beginning of the thermal process, and then further decomposes as temperature increases, and at 700 ℃ BTO nanoparticles begin to appear. It sug- gests that the YBCO film embedded with BTO nanoparticles, whose critical current density （Jc） is enhanced, is successfully prepared by an easily scalable chemical solution deposition technique.     

Conversion behavior comparison of TFA–MOD and non-fluorine solution-deposited YBCO films

The densification behavior during conversion of YBa₂Cu₃O_7−x (YBCO) films formed by the trifluoroacetate (TFA)-based metal–organic deposition (MOD) technique was compared to a non-fluorine oxycarbonate-based MOD process and nitrate-based polymer-assisted deposition (PAD). The critical current densities obtained in all processes exceeded 10⁶ A/cm² in films at least 300 nm thick. Rapid densification of films was observed in all processes, beginning at 700 °C in the TFA and PAD processes and 650 °C in the oxycarbonate process. YBCO nucleation occurred shortly after densification began in all processes. Residual carbon measurements were performed using wavelength dispersive spectroscopy (WDS). Carbon persisted in films from all processes until after densification began, but it was reduced to background levels soon after YBCO nucleation. Film density and second phase morphology were controlled through adjustments to the ambient oxygen partial pressure. Morphological evidence of extensive transient liquid phase formation was observed in PAD films and is consistent with the densification and nucleation behavior. The common behavior between the PAD, oxycarbonate–MOD, and TFA–MOD processes suggests that a melt forms in all systems, but the extent of this melt varies.     

Fabrication of YBCO／YSZ and YBCO／MgO thick films using electrophoretic deposition with top-seeded melt growth process

Superconducting thick films were grown on single crystals MgO and YSZ by electrophoretic deposition with Y_2BaCuO_5(Y211) addition. YBCO thick films were then accomplished by sintering the precursor films above the peritectic temperature. Single crystals of MgO (3×3×0.5 mm^3) were used as top-seed to control crystal structure of the thick films. As shown by scanning electron microscopy, the morphologies of YBCO/YSZ and YBCO/MgO thick films are spherulitic texture and platelet type. The critical temperature is ～89 K for the YBCO/YSZ thick film; the onset transition temperature is 86.4 K and the transition width is ～3 K for YBCO/MgO thick film. The critical current densities (as determined by Bean model) are, in A/cm^2, 3870 (77 K) for YBCO/YSZ thick films and 2399 (77 K) for YBCO/MgO thick films, which are comparable to the best J_c reported of the thick films prepared by the same method.     

Nanostructures and luminescence properties of porous ZnO thin films prepared by sol–gel process

ZnO thin films containing nano-sized pores were synthesized on solid substrates through a sol–gel process by accommodating cetyl-trimethyl-ammonium bromide (CTAB) as an organic template in the precursor solution. By X-ray diffraction the resultant ZnO films were found to possess ordered pore arrays forming lamellar structure with the spacing between two adjacent pores being ∼3.0 nm. Photoluminescence measurements indicated that the surfactants effectively passivated the surface defects of the ZnO films responsible for the green emission. Al doping was found to improve not only the lamellar structure of the pore arrays but also the near-band-gap emission intensity while the suppression effect of CTAB on the green emission remained undisturbed. With a proper control of doping level, the optical property as well as the structural integrity can be tailored to augment the potential of ZnO films for the optoelectronics and sensor applications.     

Electrical and optical properties of Sb-doped ZnO thin films synthesized by sol–gel method

Sb-doped ZnO thin films with different values of Sb content （from 0 to 1.1 at.%） are deposited by the sol-gel dip- coating method under different sol concentrations. The effects of Sb-doping content, sol concentration, and annealing ambient on the structural, optical, and electrical properties of ZnO films are investigated. The results of the X-ray diffraction and ultraviolet-visible spectroscopy （UV-VIS） spectrophotometer indicate that each of all the films retains the wurtzite ZnO structure and possesses a preferred orientation along the c axis, with high transmittance （〉 90%） in the visible range. The Hall effect measurements show that the vacuum annealed thin films synthesized in the sol concentration of 0.75 mol/L each have an adjustable n-type electrical conductivity by varying Sb-doping density, and the photoluminescence （PL） spectra revealed that the defect emission （around 450 nm） is predominant. However, the thin films prepared by the sol with a concentration of 0.25 mol/L, despite their poor conductivity, have priority in ultraviolet emission, and the PL peak position shows first a blue-shift and then a red-shift with the increase of the Sb doping content.     

Temperature dependent structural and optical properties of nanocrystallineCdO thin films deposited by sol–gel process

Nanocrystallites of cadmium oxide (CdO) thin films were deposited by sol–gel dip coating technique on glass and Si substrates. XRD and TEM diffraction patterns confirmed the nanocrystalline cubic CdO phase formation. TEM micrograph of the film revealed the manifestation of nano CdO phase with average particle size lying in the range 1.6–9.3 nm. UV–Vis spectrophotometric measurement showed high transparency (nearly 75% in the wavelength range 500–800 nm) of the film with a direct allowed bandgap lying in the range 2.86–3.69 eV. Particle size has also been calculated from the shift of bandgap with that of bulk value for the films for which the particles sizes are comparable to Bohr exitonic radius. The particle size increases with the increase in annealing temperature and also the intensity of XRD peaks increases which implies that better crystallinity takes place at higher temperature.This revised version was published online in August 2005 with a corrected issue number.     

Structure and properties of DLC–MoS2 thin films synthesized by BTIBD method

Diamond-like carbon (DLC)–MoS₂ composite thin films were synthesized using a biased target ion beam deposition (BTIBD) technique in which MoS₂ was produced by sputtering a MoS₂ target using Ar ion beams while DLC was deposited by ion beam deposition with CH₄ gas as carbon source. The structure and properties of the synthesized films were characterized by X-ray diffraction, X-ray absorption near edge structure (XANES), Raman spectroscopy, nanoindentation, ball-on-disk testing, and corrosion testing. The effect of MoS₂ target bias voltage, ranging from −200 to −800 V, on the structure and properties of the DLC–MoS₂ films was further investigated. The results showed that the hardness decreases from 9.1 GPa to 7 GPa, the Young?s modulus decreases from 100 GPa to 78 GPa, the coefficient of friction (COF) increases from 0.02 to 0.17, and the specific wear rate coefficient (k) increases from 5×10⁻⁷ to 5×10⁻⁶ mm³ N⁻¹ m⁻¹, with increasing the biasing voltage from 200 V to 800 V. Also, the corrosion resistance of the DLC–MoS₂ films decreased with the raise of biasing voltage. Comparing with the pure DLC and pure MoS₂ films, the DLC–MoS₂ films deposited at low biasing voltages showed better tribological properties including lower COF and k in ambient air environment.     

Effect of preheating temperatures on microstructure and optical properties of Na-doped ZnO thin films by sol–gel process

The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band.     

Correlation between structural and giant magnetoresistance properties of Fe–Ag nanogranular films

Fe _x Ag_1?x granular thin-films, with the atomic Fe concentration, x, ranging from 0 up to 0.5, were deposited by dc magnetron co-sputtering. The giant magnetoresistance (GMR) intensity is maximum at x _I  = 0.32, while the maximum of GMR efficiency, γ, i.e., the change of GMR intensity for a unit change of reduced squared magnetization, is observed at x _γ = 0.26. Owing to the spin-dependent scattering features, the GMR intensity and γ depend on both the concentration and the arrangement of the magnetic material. Therefore, to explain the difference between x _I and x _γ and to understand how the structural properties affect the magnetoresistive behaviour, we performed magnetization, Mössbauer and X-ray diffraction measurements as a function of x. X-ray data indicate that the granular films exhibit three different regimes: for x < 0.2, they can be described as a Fe–Ag solid solution; for 0.2 < x < 0.32 the Fe–Ag solid solution is still observed and very small Fe precipitates are found; finally, for x > 0.32, a Fe–Ag saturated solid solution is detected, containing bcc Fe clusters whose size is about 10 nm. Differently, for all the concentrations, magnetization data show the presence of Fe precipitates, whose size increases with x, and the Mössbauer investigation confirms this picture. We find that the samples grown at x = x _γ display the finest Fe dispersion within the Ag matrix, as the Fe–Ag solid solution is nearly at saturation and the Fe cluster size is of the order of a few nanometers; this arrangement possibly maximizes the magnetic/non-magnetic interface extension thus enhancing the GMR efficiency. If x is slightly increased, the increase in total Fe content compensates the GMR efficiency reduction, so the GMR intensity maximum is observed.     

Effect of annealing temperature on the structural and optical properties of ZnO thin films prepared by sol–gel method

In this work, ZnO thin films were synthesized by sol–gel method on glass substrates followed by calcinations on different temperatures. The effect of annealing temperature on the structure and optical properties of the films was studied. The structural characteristics of the samples were analyzed by X-ray diffraction and atomic force microscope. The optical properties were studied by a UV-visible spectrophotometer. The results show that all the prepared ZnO thin films have a high preferential oriented c-axis orientation with compact hexagonal wurtzite structure. With the increasing annealing temperature (mse.ufl.edu), the intensity of (002) peak, particle size, surface RMS roughness, and absorbance of the ZnO thin films were increased as well. On the contrary, the transmittance and optical band gaps were decreased.     

Influence of post-deposition annealing on the structural and optical properties of ZnO thin films prepared by sol–gel and spin-coating method

Thin films of zinc oxide have been deposited onto (0001) sapphire substrate by sol–gel and spin-coating methods. The XRD pattern showed that the crystallinity of the annealed ZnO films had improved in comparison with that of the as-grown films. Photoluminescence spectra revealed a two-line structure, which is identified in terms of UV emission and defect-related emission. The emission intensity was found to be greatly dependent on heat treatment. Host phonons of ZnO and a shift of the _E2$E_2$ (high) peak from its position have been observed from Raman spectra. The surface morphologies of the film had been improved after annealing was observed from AFM images.     

Optimization and improvement of TIPS–pentacene transistors (OTFT) with UV–ozone and chemical treatments using an all-step solution process

We fabricated an organic thin-film transistor (OTFT) using an all-step solution process. The printed layers, in which the electrode (silver), dielectric layer (BaTiO₃–PMMA), source–drain layer, and semiconductor 6,13-Bis(triisopropylsilylethynyl)pentacene(TIPS–pentacene), were optimized using roll-to-roll, an inkjet printer, and drop-casting. After coating the source–drain layer, we applied ultraviolet (UV)–ozone and self-assembled monolayer (SAM) treatments to the composite layer. The OTFTs treated with the UV–ozone and SAM treatments were found to exhibit excellent performance and good properties in comparison to silicon-based OTFTs.     

Investigation of microstructure and?photo-magnetic properties of?sulfur-doped DLC nanocomposite films by?electrochemical method

Sulfur-doped DLC nanocomposite films have been successfully deposited by the electrochemical method using the mixture of methanol and thiofuran as the precursor at ambient atmospheric pressure. In contrast to DLC film, the effects of sulfur incorporation on the microstructural transformation and properties of sulfur-doped DLC nanocomposite films were investigated in detail in terms of atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectrum and photoluminescence and magnetic tests. The experimental results showed that the unexpected organic molecular structure was formed like sulfone or thiols in sulfur-doped DLC nanocomposite films, and the concentration of sulfur in films was readily manipulated by the volume ratio of thiofuran to methanol. Meanwhile, the sp³-hybridized carbon content gradually decreased in films as the volume of thiofuran increased. Furthermore, sulfur-doped DLC nanocomposite films showed the monochromatic photoluminescence performance with a wide band centered at 510 nm, which could be attributed to carrier localization within an increasing sp² clusters and the defects along with the sulfur doping. Particularly, ferro-like magnetic performance of sulfur-doped DLC nanocomposite film might originate from the magnetic moment of localized sp² clusters with different charged carriers near the Fermi level after sulfur incorporation.     

Optical, electrical and morphological properties of p-type Mn-doped SnO2 nanostructured thin films prepared by sol–gel process

SnO₂ thin films doped with various manganese concentrations were prepared on glass substrates by sol–gel dip coating method. The decomposition procedure of compounds produced by alcoholysis reactions of tin and manganese chlorides was studied by thermogravimetric analysis (TGA). The effects of Mn doping on structural, morphological, electrical and optical properties of prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Hall effect measurement, Fourier Transform Infrared (FTIR) spectral analysis, UV–Vis spectrophotometry, and photoluminescence (PL) spectroscopy. The results of the X-ray diffraction show that the samples are crystalline with a tetragonal rutile structure and the grain size decreases with increasing the doping concentration. The SEM and AFM images demonstrate that the surface morphology of the films was affected from the manganese incorporation. The Sn_1?x Mn _x O₂ thin films exhibited electrically p-type behavior in doping level above x=0.035 and electrical resistivity increases with increase in Mn doping. The optical transmission spectra show a shift in the position of absorption edge towards higher wavelength (lower energy). The optical constants (refractive index and extinction coefficient) and the film thickness were determined by spectral transmittance and using a numerical approximation method. The oscillator and dispersion energies were calculated using the Wemple–DiDomenico dispersion model. The estimated optical band gap is found to decrease with higher manganese doping. The room-temperature PL measurements illustrate the decrease in intensity of the emission lines when content of Mn is increased in Mn-doped SnO₂ thin films.     

Exact solution of Schrdinger equation with q-deformed quantum potentials using Nikiforov–Uvarov method

In this paper,we present the exact solution of the one-dimensional Schrdinger equation for the q-deformed quantum potentials via the Nikiforov–Uvarov method.The eigenvalues and eigenfunctions of these potentials are obtained via this method.The energy equations and the corresponding wave functions for some special cases of these potentials are briefly discussed.The PT-symmetry and Hermiticity for these potentials are also discussed.     

AlN thin films prepared by ArF plasma assisted PLD. Role of process conditions on electronic and chemical–morphological properties

Aluminium nitride thin films were deposited on n-Si <100> substrates by RF plasma activated reactive pulsed laser deposition (PLD). An ArF excimer pulsed laser, 10 Hz and 2.5 J/cm² energy fluence, has been used to ablate a pure Al target in a reactive atmosphere of N₂ plasma (generated by a RF source), at varying processing parameters (substrate temperature, time, and N₂ plasma configuration). We studied the dependence and correlation of structural and electronic properties with the experimental conditions. The chemical composition of deposited material has been determined by both Raman and X-ray photoelectron spectroscopy (XPS). Electrical resistivity has been evaluated by the sheet resistance method. Both spectroscopic characterizations (Raman and XPS) show a strong dependence in the formation of AlN on the deposition temperature. At low temperatures, there is little formation of nitride, with a prevalence of aluminium oxide, while at higher temperatures the N uptake increases, with AlN formation. Raman analysis also highlights the formation of nano-structures, for temperatures ≥400^°C. These material characteristics have a fundamental influence on the electronic properties. Indeed, electrical resistivity properties have been found to be strongly dependent on the film structure, nitrogen incorporation, and presence of mixed oxide compounds, closely related to deposition temperature.     

Magnetic properties of anisotropic Pr–Fe–B films with different deposition rates and pressures

Anisotropic Pr–Fe–B films with hard magnetic properties have been prepared by DC magnetron sputtering on heated Si (100) substrates. The influences of thickness, deposition rate and sputtering gas pressure on the magnetic properties of Pr–Fe–B films were investigated. It is found that the magnetic properties are sensitive to deposition rate and sputtering gas pressure. High deposition rate and argon pressure result in a high coercivity and a low remanence.     

Structure and magnetic properties of Co–Ni–Li ferrites synthesized by citrate precursor method

Nanoparticles of Co_0.5Ni_0.5−2xLi_xFe_2+xO₄ with x ranging from 0.00 to 0.25 in steps of 0.05 were prepared by using citrate precursor method. The microstructure and the magnetic properties of the as-prepared nanosamples and the effect of increasing Li¹⁺ ions on their physical properties were studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), particle size analyzer (PSA), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) were used to investigate the samples. The XRD analysis confirmed the cubic spinel phase formation of the prepared samples, while TEM images and PSA ensure the nanostructural features of them. The FTIR spectra reveal the presence of two prominent absorption bands v₁ and v₂ in the range of 600 and 400 cm⁻¹ which are usually attributed to the tetrahedral and octahedral complexes of the spinel lattice, respectively. The change of v₂ gradually towards lower frequency and the slightly change of v₁ were explained depending on the effect of increasing Li¹⁺ content on the bond length of B-site metal ions and the spin canting of A-site metal ions, respectively. Saturation magnetization and remnant magnetization were found to increase with adding Li¹⁺ ions up to x=0.15 and then to decrease again, while coercivity decreases monotonically by increasing Li¹⁺ ions. The change in magnetic properties by adding Li¹⁺ ions is explained as to be dependent on many factors such as crystallite size, measured density, porosity, expected cation distribution, A–B exchange interactions, and magnetocrystalline anisotropy.     

Synthesis and characterization of nanostructured strontium hexaferrite thin films by the sol–gel method

Nanostructured single phase strontium hexaferrite, SrFe₁₂O₁₉, thin films have been synthesized on the (100) silicon substrate using a spin coating sol–gel process. The thin films with various Fe/Sr molar ratios of 8–12 were calcined at different temperatures from 500 to 900 °C. The composition, microstructure and magnetic properties of the SrFe₁₂O₁₉ thin films were characterized using Fourier transform infrared spectroscopy, differential thermal analysis, thermogravimetry, X-ray diffraction, electron microscopy and vibrating sample magnetometer. The results showed that the optimum molar ratio for Fe/Sr was 10 at which the lowest calcination temperature to obtain the single phase strontium hexaferrite thin film was 800 °C. The magnetic measurements revealed that the sample with Fe/Sr molar ratio of 10, exhibited higher saturation magnetization (267.5 emu/cm³) and coercivity (4290 Oe) in comparison with those synthesized under other Fe/Sr molar ratios.     

Optical properties and structures of silver thin films deposited by magnetron sputtering with different thicknesses

A series of thin Ag films with different thicknesses grown under identical conditions are analyzed by means of spectrophotometer. From these measurements the values of refractive index and extinction coefficient are calculated. The films are deposited onto BK7 glass substrates by direct current (DC) magnetron sputtering. It is found that the optical properties of the Ag films can be affected by films thickness. Below critical thickness of 17 nm, which is the thickness at which Ag films form continuous films, the optical properties and constants vary significantly with thickness increasing and then tend to a stable value up to about 40 nm. At the same time, X-ray diffraction measurement is carried out to examine the microstructure evolution of Ag films as a function of films thickness. The relation between optical properties and microstructure is discussed.