Preparation of aluminum doped zinc oxide targets and RF magnetron sputter thin films with various aluminum doping concentrations

In this work, aluminum doped zinc oxide (AZO) ceramic targets were prepared from ZnO powder and Al2O3 powder with varying amounts of Al2O3 doped in a range of 1-5 wt%. The mixed ZnO and Al2O3 powders were pressed at a pressure of 80 MPa into disks and sintered at 1,300 °C for 5 h in air. The crystal structures of the sintered targets were characterized by X-ray diffraction (XRD) technique. It was found that the XRD spectra showed a hexagonal (wurtzite) structure of ZnO for all Al2O3 doped films. However, as the amount of Al2O3 increased over 2 wt%, the gahnite (ZnAl2O4 ) phase could be observed in the XRD spectra. The AZO films were deposited on glass slides at room temperature and post-annealed at 500 °C in a vacuum for 1 h. The film structures, Al/Zn ratio between the Al and Zn atoms, and the electrical properties were characterized. It was found that an increase of Al2O3 content in the target gave a higher Al doping concentration in the film which resulted in more Al substitutions in the Zn sites which in turn resulted in an increase of carrier concentration. The crystal structure of the AZO films deposited from undoped and 1 wt% Al2O3 -doped targets showed the (002) preferred orientation and drastically decreased at higher Al doping concentrations. The mobility of the charge carrier was affected by lower crystallinity due to grain boundary scattering. In addition, the excess Al in the film may play a role as impurity scattering centers. A decrease of Hall mobility resulted in increased resistivity. The minimum resistivity of 2.01x10-3 Ω.cm could be achieved for the AZO films deposited from 1 wt% Al2O3 -doped ZnO targets

Evaluating Post-Treatment Effects on Electrospun Nanofiber as a Support for Polyamide Thin-Film Formation

Poly(acrylonitrile-co-methyl acrylate) (PAN-co-MA) electrospun nanofiber (ENF) was used as the support for the formation of polyamide (PA) thin films. The ENF support layer was post-treated with heat-pressed treatment followed by NaOH hydrolysis to modify its support characteristics. The influence of heat-pressed conditions and NaOH hydrolysis on the support morphology and porosity, thin-film formation, surface chemistry, and membrane performances were investigated. This study revealed that applying heat-pressing followed by hydrolysis significantly enhances the physicochemical properties of the support material and aids in forming a uniform polyamide (PA) thin selective layer. Heat-pressing effectively densifies the support surface and reduces pore size, which is crucial for the even formation of the PA-selective layer. Additionally, the hydrolysis of the support increases its hydrophilicity and decreases pore size, leading to higher sodium chloride (NaCl) rejection rates and improved water permeance. When compared with membranes that underwent only heat-pressing, those treated with both heat-pressing and hydrolysis exhibited superior separation performance, with NaCl rejection rates rising from 83% to 98% while maintaining water permeance. Moreover, water permeance was further increased by 29% through n-hexane-rinsing post-interfacial polymerization. Thus, this simple yet effective combination of heat-pressing and hydrolysis presents a promising approach for developing high-performance thin-film nanocomposite (TFNC) membranes