Papers by Keyword: Co-Sputtering

Abstract: This study reports on the effect of Gd concentrations on the properties of Gd-doped ZnO films. The films were prepared using co-sputtering method at room temperature. Characterization tools such as X-ray diffraction (XRD), atomic force microscopy (AFM), and vibrating sample magnetometer (VSM) were used to analyze the properties of the prepared films. XRD results observed that all the films are well crystalline and designated to the hexagonal wurtzite structure of ZnO with no secondary phases, which confirmed the successful of doping the Gd into ZnO. Topography analysis from AFM discovered the increase of Gd concentrations of Gd-doped ZnO films leads to the increase in grain size and rougher surface of the films. The magnetization of the films effectively depends on the Gd concentrations, which the diamagnetic behavior changed to ferromagnetic behavior upon Gd doping. A film with higher Gd doping concentration is more effective than lower Gd doping in terms of saturation magnetization (M_s), coercivity (H_c) and remanent magnetization (M_r). These findings revealed that optimizing the Gd concentration is very crucial in enhancing the magnetic properties of Gd-doped ZnO films.

Abstract: Undoped ZnO, Gd-doped ZnO, and (Al, Gd) co-doped ZnO thin films were synthesized using the co-sputtering technique on a glass substrate. XRD data confirmed all the films are hexagonal structures with dominant (002) diffraction peaks. There are no secondary phases or other peaks detected except for ZnO which proves well incorporation of Gd³⁺ and Al³⁺ ions into ZnO ions for Gd and (Al, Gd) co-doping ZnO thin films. The EDX analysis shows the composition of Al, Gd, Zn, and O for (Al, Gd) co-doped ZnO thin films considering the successfully doping of Gd and Al into ZnO structure by this deposition method. As compared with undoped ZnO and Gd-doped ZnO, the electrical properties of (Al, Gd) co-doped ZnO showing a good enhancement of carrier concentration (2.34 x 10²⁶ m^-3) and electrical conductivity (1.41 x 10⁵ Ωm^-1) whereas the resistivity is low about 7.11 x 10⁴ Ωcm.

Abstract: We prepared ytterbium and silver co-doped tantalum-oxide (Ta₂O₅:Yb,Ag) thin films using a simple co-sputtering method and evaluated photoluminescence (PL) properties of the films after annealing. We found that a PL peak at a wavelength of 980 nm due to Yb³⁺ can be strongly enhanced by Ag doping. From X-ray diffraction measurements, we found that Ag₂Ta₈O₂₁ and orthorhombic Ta₂O₅ crystalline phases are very important in order to enhance the 980-nm peak observed from our Ta₂O₅:Yb,Ag thin films. Because of the human-body transmittability of the 980-nm wavelength, such films are applicable to a novel real-time X-ray dosimeter system.

Abstract: We report the initial results of using co-sputtered Pt:Ti 80:20 at. % composition ratio metallization as a diffusion barrier against gold (Au) and oxygen (O), as an interconnect layer, as well as forming simultaneous ohmic contacts to n-and p-type 4H-SiC. Having a single conductor with such combined multi-functional attributes would appreciably reduce the fabrication costs, processing time and complexity that are inherent in the production of SiC based devices. Auger Electron Spectroscopy, Focused Ion Beam-assisted Field Emission Scanning Electron Microscopy and Energy Dispersive Spectroscopy analyses revealed no Au and O migration to the SiC contact surface and minimal diffusion through the Pt:Ti barrier layer after 15 minutes of exposure at 800 oC in atmosphere, thus offering potential long term stability of the ohmic contacts. Specific contact resistance values of 7 x 10^-5 and 7.4 x 10^-4 Ω-cm² were obtained on the n (N_d=7 x 10¹⁸ cm^-3) and p (N_a=2 x 10²⁰ cm^-3) -type 4H-SiC, respectively. The resistivity of 75 μΩ-cm was obtained for the Pt:Ti layer that was sandwiched between two SiO₂ layers and annealed in pure O ambient up to 900 °C, which offers promise as a high temperature interconnect metallization.

Abstract: CZTS thin films are fabricated by sulfurizing co-sputtered metallic precursor CuZnSn layers under H2S atmosphere. The precursor layers are Cu-poor, Zn-rich deposited and the fabricated films are about 2 µm in thickness. A closed-tube process is preferred with regard to its producing large closely pack grains with smooth surface. XRD and Raman confirm the CZTS structure and the impurities on the surface are removed after suitable chemistry treatments. The band gap of the CZTS is determined to be 1.48 eV by extrapolation. Some more CZTS films are product with slightly changed parameters, sulfurization time, temperature and concentration of H₂S, respectively. It is supposed that beside sulfurization time, the temperature could be more significant than concentration of H₂S in the closed system.

Abstract: SiO_x barrier films were deposited on poly (ethylene terephthalate) (PET) by radio frequency (RF) magnetron co-sputtering with double targets. The films deposited by co-sputtering were denser and smoother because different energy particles sputtering from double targets grew small islands to weaken shadowing effect which greatly reduce the interval gaps. The water vapor and oxygen transmission of SiO_x films deposited by co-sputtering decreased to 0.31 cc/m²/day, 0.27 g/m²/24h respectively.

Abstract: Antimony and tellurium were deposited on K9 glass via direct current and radio frequency magnetron co-sputtering. Antimony telluride thermoelectric thin films were simultaneously synthesized without post treatment. The influence of the sputtering power of Te and annealing of Sb-Te fabricated by magnetron sputtering were investigated. The maximum Seebeck coefficient of Sb-Te film was 212 μV/K which was obtained at the sputtering power of Sb 4W and Te 60W separately. When annealed at 300 °C, the electrical resistivity and Seebeck coefficient of the film are 6.67x10⁴ S/m and 119 μV/K. The power factor increased to the highest value of 9.4×10^-4 W/mK² from 4×10^-5 W/mK² after post treatment of the as-deposited film.

Abstract: TaN–Cu and TaN-Ag nanocomposite films were deposited by reactive co-sputtering on Si. The films were then annealed using RTA (Rapid Thermal Annealing) at 400 °C for 2, 4, 8, 15 minutes respectively to induce the nucleation and growth of metal particles in TaN matrix and on film surface. The samples were then tested for their anti-bacterial behaviors against Gram-negative and Gram-positive bacteria. The results were compared with the solubility of Ag and Cu in a buffer solution. Under similar ion concentrations, it is concluded that Ag ion or TaN-Ag is more effective against E. Coli (Gram-negative), while Cu ion or TaN-Cu is more effective against Staphylococcus aureus (Gram-positive).

Abstract: In the vacuum film coating field, the co-sputtering method by two or more targets has been widely used for coating the composite film consisted of a variety of component elements. In this paper, a typical co-sputtering system is studied which composes the twin round planar magnetron sputtering targets settled symmetrically and slantways towards a single flat substrate with self-rotation. A model is set up to describe the non-dimensional relationship between the film thickness and the structural parameters of co-sputtering system, such as distance of the substrate-to-target , symmetrical eccentricity , translation length and obliquity angle of target . On the assumption that the sputtered particles are emitted in the direction of cosine distribution and fly straightly without collision scattering, the depositing rate distribution, film thickness distribution, the utilization ratio of the target sputtering material, and the fluctuant ratio of the components from two targets are calculated. Some of simulating examples are given by use of Matlab software.

Abstract: The Al-Cu-Fe nano films were successfully deposited by magnetron co-sputtering with the Al, Cu and Fe independent targets. The surface morphologies, microstructure and composition of the films were analyzed by SEM and XRD. The bonding strength, friction coefficient, nanohardness and elastic modulus of the films before and after annealing at 600 °C were determined by nano-indentation and nano-scratch. The results show that the bonding strength of the film with stainless steel substrate is the highest among these substrates. The friction coefficient of the film for pure Cu substrate is 0.17. New fine β phases with approximate quasicrystalline structure are formed in Al-Cu-Fe films after annealing at 600 °C. Furthermore, the hardness and elastic modulus of the films are obviously increased respectively.