Papers by Keyword: Thin Film

Abstract: Li-doped ZnO thin films were grown on quartz substrates by radio frequency magnetron sputtering and In-situ annealing. The structural, electrical and optical properties of Li-doped ZnO films strongly depend on the annealing oxygen pressure. XRD and AFM analysis indicate that the ZnO films possess a good crystallinity with c-axis orientation, uniform thickness and dense surface. Optical transmission spectra show a high transmittance (~85%) in the visible region. Hall measurement demonstrates that ZnO films have p-type conduction with a Hall mobility of 5.0 cm²/Vs, resistivity of 0.97Ωcm and carrier concentration of 1.60×10¹⁷cm^-3 when annealing oxygen pressure is 1Pa.

Abstract: Aluminum oxide film doped with Ce³⁺ has been deposited by the medium frequency reactive magnetron sputtering technique. The photoluminescence emission from these films show peaks at range of 374-405 nm. The relative intensity of these peaks is strongly dependent on the amount of Ce incorporated in the films. The presence of Ce³⁺ as well as the stoichiometry of these films has been determined by energy dispersive x-ray spectroscope (EDS) measurements. It is proposed that the light emission observed generated by luminescent center associated with cerium chloride molecular rather than to atomic cerium impurities. The reason for a dominance of the lower energy transition as the amount of Ce³⁺ in the oxide films is increased is that the energy difference of 4f¹and 5d¹ decreases, with the increase of the Ce³⁺ concentration. These luminescent films are potentially good candidates for photonics applications.

Abstract: Interference image processing is the key technology of optical interference measurement. This paper introduced the problems on automatic interference fringe processing in absolutely measurement based on laser interference, digital image processing technology. The image acquisition of the SiO₂ film and the pre-processing of interferogram was performed.Decimal part of the interference fringes is obtained. Using high-resolution image acquisition system and computer reads and processes the interference image, replaces the traditional work of skilled workers of high intensity for a long time and improves the film thickness measurement accuracy.

Abstract: The single-crystalline nanobelts of monoclinic Ni(SO₄)_0.3(OH)_1.4 have been synthesized on a large scale through a convenient, low-temperature hydrothermal method. The influences of reaction time, pH value, concentration of ammonia on the phase and shape evolution of nanobelts were systematically investigated. It was found that the initial layered Ni(OH)2 thin films as intermediates could be split and converted into the monoclinic Ni(SO₄)_0.3(OH)_1.4 nanobelts through SO₄^2- ions inserting process. The formation mechanism of nanobelts involved in the inserting process and the corresponding drive force have been investigated in detail by means of X-ray diffraction (XRD), and scanning electron microscopy (SEM), FT-IR spectra and pH value analyses. In addition to, we have also found that the ammonia molecules acted as both weak base and ligand agent was crucial to the controlling nucleation and inserting process in the formation process of nanobelts.

Abstract: PZT thin film was prepared on platinized Si substrates by liquid-source mist microwave plasma enhanced chemical vapour deposition. Using citric amine and ethylene glycol as chelating agent, a homogeneous, stable water solvent sol was prepared successfully, which was suitable to develop PZT thin film by LSMPECVD. From the analysis of FTIR spectra, the special functions of chelating agents were identified. It shows that this deposition process is nonuniform nucleation, the PZT thin film grew with island model. Prior to fill the blank sites on the substrate, the latter deposited PZT congregated together to reduce surface energy. The morphology and structure were characterized by SEM and XRD analysis.

Abstract: Superhydrophobic surface was prepared by hydrothermal method on copper substrate via immersing the clean pure copper substrate into the mixed solution of H₂O₂ and C₂H₅OH, and then the substrate was heated at 100°C for 1.5 h, followed by modifying with stearic acid. The product was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The wettability of the products was also investigated. It was found that the as-prepared surface had a high water contact angle of about 153°. SEM images of the film showed that many irregular micro-nano sheets distributed on the surface in a random pattern. The special porous architecture, with the low surface energy leads to the surface superhydrophobicity.

Abstract: Metal oxynitride (V_xON, Cr_xON) thin film has been fabricated by reactive dc sputtering method and annealing process. Its electrochemical properties are investigated in a M_xON/Li cell. The reversible specific capacities are around 830 mAh g^-1 for V_xON and 730 mAh g^-1 for Cr_xON. By using selected-area electron diffraction and X-ray photoelectron spectroscopy measurements, New electrochemical reaction mechanism is uncovered, which should be responsible for its good electrochemical performance.

Abstract: Thin films of single-walled carbon nanotubes (SWNTs) attached to an ITO surface (SAM–ITO) self-assembled in advance from 3-aminopropyltrimethoxysilane through amide covalent bonds were prepared. The SWNTs were safely obtained via a two-step process assisted by microwave radiation, which were soluble in aqueous and organic media. However, the CV behavior of SAM–ITO in acidic aqueous systems showed unexpected oxidation signals due to redox reactions involving the defects and sidewalls of soluble functionalized SWNTs. It was found that, after a conductive polymer of polyaniline was chemically incorporated onto the surface of the SWNTs by using electropolymerization method, the CV data showed a single reversible redox couple, which indicated a more stable state.

Abstract: N-type Bi₂(Te_0.95Se_0.05)₃ thermoelectric thin films with thickness 800 nm have been deposited on glass substrates by flash evaporation method at 473 K. The structures, morphology of the thin films were characterized by X-ray diffraction and field emission scanning electron microscope, respectively. Thermoelectric properties of the thin films have been evaluated by measurements of Seebeck coefficient and electrical resistivity at 300 K. Annealing effect on Seebeck coefficient and electrical resistivity of the thin films was examined in the temperature range 373–573 K. When annealed at 473 K for 1 h, Seebeck coefficient and electrical resistivity are –180 μV/K and 2.7 mΩcm, respectively. Thermoelectric power factor is improved to 12 µW/cmK².

Abstract: The effects of the polyhedral oligomeric silsequioxanes (POSS) in stacked poly(methyl methacrylate) (PMMA) film samples were investigated in two different film thicknesses, ~50 and ~660 nm. The types of the POSS include methacryl-, octaisobutyl-, and octasilane-POSS. The glass transition temperature (T_g) and isothermal physical aging was depressed by the reduction of film thickness. Among POSS molecules used in this work, methacryl-POSS was the greatest effect in both T_g and relaxation enthalpy (DH_Relax) due to the physical aging. The Kohlrausch-Williams-Watts (KWW) relaxation function was used to further understand the effect of POSS and film thickness on the physical aging.