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Understanding of structural, optical, and electrical properties of thin films are very important for a reliable device performance. In the present work, the effect of postdeposition annealing on stoichiometric SrTiO3 (STO) thin films grown by radio frequency magnetron sputtering at room temperature on p-type Si (100) and quartz substrates were studied. Highly transparent and well adhered thin films were obtained in visible and near infrared regions. As-deposited films were amorphous, while nanocrystalline and polycrystalline phases of the STO thin films formed as a function of annealing temperature. Films annealed at 300 degrees C showed nanocrystallinity with some amorphous phase. Crystallization started after 15 min annealing at 700 degrees C, and further improved for films annealed at 800 degrees C. However, crystallinity reduced for films which were annealed at 900 degrees C. The optical and electrical properties of STO thin films affected by postdeposition annealing at 800 degrees C: E-g values decreased from 4.50 to 4.18 eV, n(lambda) values (at 550 nm) increased from 1.81 to 2.16. The surface roughness increased with the annealing temperature due to the increased crystallite size, densification and following void formation which can be seen from the scanning electron microscopy images. The highest dielectric constants (46 at 100 kHz) observed for films annealed at 800 degrees C; however, it was lower for 300 degrees C annealed (25 at 100 kHz) and as-deposited (7 at 100 kHz) STO films having similar to 80 nm thickness. (C) 2017 American Vacuum Society.

A major application of microfluidic paper-based analytical devices (mu PADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, mu PADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop mu PADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop mu PADs within 10 min Was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141 degrees +/- 1) was obtained using the microwave irradiation method over a period of 7 min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si-O-Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed mu PADs was performed by utilizing the rapid urease test as a model test system. The detection limit of the developed mu PADs was measured as 1 unit ml(-1) urease enzyme in detection zones within a period of 3 min. The study findings suggested that a combination of microwave irradiation with inkjet-printing technique could improve the fabrication method of mu PADs, enabling faster production of mu PADs that are easy to use and cost-effective with long shelf lives. (C) 2016 Elsevier B.V. All rights reserved.