Papers by Keyword: Preferred Orientation

Abstract: In this present work, TiN films with various thicknesses (from 0.3 μm to 2 μm) were deposited by DC reactive magnetron sputtering on Ti6Al4V substrates. The evolution of texture and microstructure were studied by X-ray diffraction and Scanning Electron Microscopy, respectively. The XRD characterization indicates that the preferred texture of TiN films is changed from (111) to (100) with increasing the film thickness. The microstructure characterization shows that their microstructure transform from continuous into columnar with increasing the TiN film thickness. It is considered these results are arised from the change of overall energy including surface energy and strain energy with the film thickness. The hardness of TiN film increases with increasing the film thickness.

Abstract: Aluminum nitride (AlN) film as a piezoelectric material has been used widely, particularly in vibration energy harvester due to its unique and enhanced properties such as high temperature resistance and compatibility with CMOS processes. In this work, AlN film with (002) preferred orientation was prepared on silicon wafers by pulse DC reactive magnetron sputtering (RMS), and the properties such as peak intensity, full width at half maximum (FWHM) and surface morphology were investigated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The preferred orientation was found to be sensitive to deposition conditions such as gas flow rate, power, bottom electrodes materials and substrates temperature. The results shows that the intensity was 1.1×10⁵ counts, the FWHM was 1.9owhen the temperature was 260°C. The film was used to fabricate the vibrated energy harvester successful and the power density reached about 3000uW/cm³ at the vibration frequency under 1g acceleration.

Abstract: This paper is focused to structure characterization of two differently electrodeposited Ni-Co alloys on the copper surface. The chemical composition of the layers was determined by the EDX analysis in the scanning electron microscope. Phase analysis was realized by diffraction in the transmission mode using synchrotron radiation. Diffraction patterns also show the preferred orientation in the coating with saccharine addition.

Abstract: Zinc Oxide (ZnO) is a wide bandgap semiconductor material which can be successfully used for wide variety of potential applications such as biosensors or acoustic resonator devices. ZnO normally crystallizes in the wurtzite structure with c-axis (001) preferred orientation. However, for bio-sensing in liquids, it is necessary to generate a shear horizontal mode wave, where the wave displacement is within the plane of the crystal surface. For generation of such a shear horizontal wave, a-axis film textures such as the (110) or (100) is necessary. This work is focused on the preferred orientation control of ZnO film prepared by RF magnetron sputtering. It is found that preferred orientation can be controlled by substrate bias and substrate temperature during deposition without the use of expensive crystalline substrates. There are three areas of operating parameters when the structure of the ZnO films is dominated by different preferred orientation. Moreover, the film annealing was performed to enhance the film structure.

Abstract: BaTiO₃ (BTO) thin films were grown on (100) SrTiO₃ (STO) single crystal substrates using the RF-magnetron sputtering technique (RFMS) in both pure argon and mixed Ar/O₂ (20% O₂) atmosphere. A La_0.5Sr_0.5CoO₃ (LSCO) layer was deposited as the bottom electrode by a 90° off-axis single-target RFMS. θ-2θ X-ray diffraction measurements showed that BTO thin films grown in both cases had a highly preferred c-axis orientation (001). From hysteresis measurements, it was confirmed that both films are ferroelectric. The ferroelectric polarizations 2Pr were 6.6 μC/cm² and 27.1 μC/cm², for the BTO films grown in pure argon and in mixed Ar/O₂ atmosphere, respectively.

Abstract: Large area (13mm*13mm) PbS thin films with (200) preferred orientation were prepared by chemical deposition. The optical properties of PbS films with annealing treatment in various forming gases with different ratio of nitrogen-oxygen (100ml/min of N₂&O₂(3:1), 100ml/min of N₂&O₂(2:1), 100ml/min of N₂&O₂(1:1), 50ml/min of O₂) were deeply analyzed. X-ray diffraction (XRD), scanning electron microscope (SEM), high and low temperature test chamber and other test methods for photosensitivity were used to investigate the structure and photoelectric properties of PbS films. The results showed that with proper amount of oxidation (when nitrogen-oxygen ratio was 1:1), the impurity barrier tended to fully grow, impurity activation energy increased to 0.314eV, dark resistance reached up to 30.2MΩ, and the photoconductive sensitivity of PbS thin film under this process was about 4 times larger compared with air annealing. According to the analysis of XRD patterns and surface morphologies of films, it can be seen that nitrogen in this process was not only to prevent PbS thin films from excessive oxidation, but also inhibited the formation of surface defects and enhanced the stability of PbS device.

Abstract: Based on the ion beam sputtering deposition technology, we adopted the reactive sputtering deposition method to accomplish the coating on the glass substrata with ZnO thin films. We used the four-factor and three-level L₉(3⁴) orthogonal experiment to obtain the best technological parameters of deposited ZnO thin films: discharge voltage 3.5KV, oxygen current capacity 8SCCM, the coil current 8A, the distance between target and substrata 140mm. The purity of the deposited ZnO thin film is 85.77%, and it has the good crystallization in orientation. The experimental results show that research and development of the ion beam sputtering source is advanced and has a good application value, and the ion beam sputtering deposition technology can be used to deposit the preferred orientation thin films with good performance. The findings have provided the experimental result and the beneficial reference for the ion beam sputtering deposition research.

Abstract: Preferred orientation of AlN films has been improved to c-axis using a highly (111) textured Pt layer. The highly textured (111) Pt layer is obtained by inserting an AlN layer between the Pt layer and substrate. Thus, Pt/AlN/substrate could be termed a substrate for preferred orientation controlled AlN films. X-ray diffraction (XRD) profiles reveal that the degree of preferred orientation of such highly (111) textured Pt layer surpasses the one originated from the crystal structure of Pt. The (2θ, ψ) intensify maps of diffracted X-ray collected as a function of the diffraction angle (2θ) and the tilting angle (ψ) exhibit that the films are perfectly (111) preferred orientated, however, they do not show in-plane texture. The (2θ, ψ) maps also demonstrate that a residual stress in films is subject to compressive.

Abstract: C₆₀ thin films were deposited on Si substrates at different evaporation temperatures using the thermal evaporation method. In this paper, an extensive study of morphology and crystallinity of the films was presented by atomic force microscopy (AFM), low angle X-ray diffraction (LA-XRD) and UV-vis spectrophotometer. It is found that a good crystalline quality along a (333) preferred orientation was observed at the 450°C evaporation temperature and an ordered sequence of fcc structure was evaluated. The 2.24eV optical energy bandgag of C₆₀ thin film corresponding to h_u→ t_1u transition between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels was also extracted.

Abstract: Ni coatings with different grain sizes and preferred orientations were produced by the control of current density during a direct current electrodepositing process. The effects of grain size reduction and preferred orientation on the oxidation behavior in air at 600°C and 960°C of Ni coatings were investigated respectively. An important and interesting result is that after oxidation at 600°C, the Ni coating obtained at lower current density has a better oxidation resistance, whereas after oxidation at 960°C, the Ni coating obtained at higher current density has a more compact scale and a better oxidation resistance. For the Ni coatings oxidation at 600°C, the oxidation behavior was mainly influenced by grain size, whereas in the case of the Ni coatings oxidation at 960°C, the oxidation behavior was only slightly influenced by grain size. The changes in oxidation behavior of Ni coatings at 960°C can be attributed to the different preferred orientation and the corresponding oxidation mechanism.