Apirak Pankiew

Fabrication of Low Cost Anodic Aluminum Oxide (AAO) Tubular Membrane and their Application for Hemodialysis

This paper reports the fabrication of AAO tubular membrane using 99.35% and 99.56% pure Al and their potential application for hemodialysis. Here we discussed the effect of impurity on membrane structure. We found that the self organized structure of AAO nanochannels minimizes impurity defects in membrane. If micro size impurity blocks the generation of nanochannels then the neighboring nanochannels bend and make branches to fulfill that gap. We observed that if impurity size is less than the AAO membrane thickness then it does not produce any micro size hole. In low grade Al the periodic hexagonal order was disturbed however there was no big difference in pore diameter. It was observed that such type of membrane do not have any leakage and it can be used for fluid filtration. The fabricated tubular membrane was used for hemodialysis successfully. The hemodialysis results show that AAO tubular membrane can be used for both diffusive and convective filtration

UV-enhanced photodetector with nanocrystalline-TiO 2 thin film via CMOS compatible process

This research presents nanocrystal titaniumdioxide (nanocrystal-TiO2) film deposition technique with CMOS compatible process [1] to extend the optical response bandwidth of silicon based photodetecting devices toward ultraviolet range [2]. The thin films were initially deposited as Titanium Nitride (TiN) using DC magnetron reactive sputtering system. It was then annealed under nitrogen atmosphere at 800°C. After analyzing crystal structures and surface morphology with X-ray diffraction and FE-SEM systems, it was found that the deposited thin films showed the crystal phase of TiO2 oriented along (200) plane of Rutile crystal structure with 50 nm grain size and increasing with film thickness. Using electroreflectance (ER) spectroscopy measurement [3], the bandgap of nanocrystal-TiO2 was revealed to be 3.16 eV. PN-heterojunction photodiodes were fabricated with Nanocrystal-TiO2/SiO2/p-Si structures. Interdigitated aluminum structures were used as electrodes. By varying the thickness of nanocrystal-TiO2 film, i.e. 30, 60, and 90 nm, the devices could response further into the UV range. The absorption edge wavelength investigated by photoresponse measurement was at 275 nm and shifting to the shorter wavelength as a function of the nanocrystal-TiO2 grain size due to quantum confinement phenomenon [4]. The nanocrystal-TiO2/SiO2/p-Si photodetector had dark current = 5.31nA (2V), photocurrent = 0.9 uA, rise time = 58 us, fall time = 47 us at 30 nm thickness of TiO2.

Crucial role of reactive pulse-gas on a sputtered Zn3N2 thin film formation

Herein, we demonstrate a powerful technique, known as reactive gas-timing (RGT) rf magnetron sputtering, to fabricate high quality Zn3N2 thin films at room temperature without applying any additional energy sources. A single phase of Zn3N2 film formation can only be obtained when a reactive pulse-gas of N2 is utilized. We find that selecting a small atomic mass of sputtered reactive gas coupled with the pulse-gas technique is very crucial to adjust the number of sputtered atoms obtained from the target and enrich the forming energy of the sputtered Zn3N2 films during the deposition process. Our results highlight that the RGT technique is a promising method to fabricate high quality sputtered compound thin films that can be applied in flexible devices. A simplified model of the materials system at the surface region of the de-nitride Zn3N2 during ion bombardment is also presented.

High Sensitive Nanocrystal Titanium Nitride EG-FET pH Sensor

Solid state pH-sensor device with high efficiency has successfully prepared by using TiN thin film as sensing membrane of extended gate field effect transistor (EG-FET) device. This research has described the physical properties and sensing characteristics of TiN membrane thin film which deposited on SiO2/Si substrate through reactive D.C. magnetron sputtering system. Thenanocrytal-TiNwith anatasestructure depended on substrate heating conditions was revealed from glancing angle x-ray diffraction. The IDS-VGS measurement in the standard buffer solutions showed that the sensitivity of fabricated TiN-EGFET pH deviceis 59.82mV/pH.

Surface Morphology and Structural Investigation of TiN Nanocrystal Thin Films Grown with Different N2 Concentration

In this work, new information on surface morphology, phase and local structure of titanium nitride (TiN) nanocrystal thin films grown with different nitrogen gas concentration by direct current (DC) magnetron sputtering is provided. Surface morphology of the thin films was studied by field emission scanning electron microscope (FE-SEM). Phase and local structure of the TiN nanocrystals were determined by X-ray diffraction spectroscopy (XRD) and X-ray absorption fine structure (XAFS). The TiN nanocrystals were prepared on silicon substrates. N2/Ar gases were used as reactive gases for sputtering Ti target. The amount of these two reactive gases was varied at different ratios (N2/Ar), i.e. 100:0, 75:25, 50:50 and 25:75 respectively. Our results suggested that sputtering Ti target with high N2/Ar gas raSubscript texttio (higher than 75%) provides good TiN layer while sputtering with low N2/Ar gas ratio (lower than 25%) gives Ti layer instead of TiN. In addition, sputtering with 50% N2/Ar gas ratio gives a multiphase system between TiN and Ti. Local structure parameters of these nanocrystal thin films are reported.

The effects of fluorine ion implantation on acrylic resin denture base

Acrylic resin denture base, with fluorine ion implantation at different doses, were compared with reference specimens without ion implantation. The specimens were measured for the quantity of fluorine released for 15 days. It was found that ion implantation caused surface modification of the resin and allowed fluorine ions to penetrate into the polymer. The specimens had the ability to release fluorine into deionized water. Furthermore, the specimens with 1015 atoms/cm2 implantation showed the highest releasing rate compared with the conditions with 1013 ions/cm2 implantation and the ones with no implantation.

An Effect of Viscosity of Coating Materials on Silicon Micro-Patterning Arrays for Superhydrophobic Surface

Two different viscous coating materials, which are Polydimethylsiloxane (PDMS) mixed with 10%wt of Dicumylperoxide (DCP), and Semifluorinate Silane (SFS), were applied to silicon micro-asperity. The cosine’s Young and viscosity of those coating materials are -0.3584,-0.3496 and 3.176x10-3, 1.339 x10-3 Pas, respectively. The rough surfaces with nine asperity shapes were studied. The results shown that, pillar shape has an effect on water contact angle (WCA): Stripe asperity cannot make the average WCA greater than 150. When consider the pillar asperity, the WCA falls between 152 and 157, which exhibits a superhydrophobic surface property. However, actual WCA of the micro-asperity coated with PDMS+10%wt of DCP is lower than that coated with SFS around 1 to 7. High viscous material makes the asperity size bigger than the design and decreases the WCA: the low viscous material is more suitable for coating on the asperities.

The Optimization of TiN Film Deposited by DC Magnetron Sputtering Provided for Al Diffusion Barrier

Titanium nitride (TiN) film has been widely used as a diffusion barrier layer for VLSI contact metallization because TiN is an excellent barrier against inter-diffusion between Al and Si substrate or silicide. In this work, we studied the properties of TiN films deposited by DC magnetron sputtering with varying N2:Ar flow rate ratio in order to optimize growth conditions and film properties provided for Al diffusion barrier purpose. The TiN films were deposited at the constant pressure level and sputtering time. The crystalline orientation, composition and electrical properties of deposited TiN films were characterized by XRD, AES-depth profile and Four Point Probe measurement, respectively. The XRD results show that the deposited TiN film has two preferred orientations of TiN(111) and TiN(200) planes. The highest intensity of the TiN(111) plane was obtained when the N2:Ar flow rate ratio was 3:1. The electrical resistivity was increased when the N2:Ar flow rate ratio was decreased. The minimum electrical resistivity is 127.8 μΩ-cm when the N2:Ar flow rate ratio is 3:1.

Oxygen Gas-Timing Control for Variety Properties of Sputtered-ZnO

In this report, we present sputtered zinc oxide (ZnO) thin films grown with different argon (Ar) and oxygen (O2) gas-timing sequence. Metallic zinc (Zn) with 5N-purity was used as a sputtering target, while Ar and O2 of 6N-purity were used as the bombard and reactive gases, respectively. The crystalline orientation, surface morphology, chemical composition, optical and electrical properties of deposited ZnO thin films were determined by XRD,AFM and UV-VIS measurement, respectively. The XRD result implied that deposition ZnO thin films at different O2 gas-timing control corresponded to the (002) plane of hexagonal ZnO structure at 2Ө = 34.4◦. Furthermore, when the reactive time of O2 was increased, the transmittance of ZnO thin films exhibited the energy gap increase from ~2.95 to ~3.18 eV, whereas the surface roughness was found to decrease. Finally, ZnO thin films were oxidized after the deposition.