K.C. Aw

Direct formation of gold nanoparticles on substrates using a novel ZnO sacrificial templated-growth hydrothermal approach and their properties in organic memory device

This study describes a novel fabrication technique to grow gold nanoparticles (AuNPs) directly on seeded ZnO sacrificial template/polymethylsilsesquioxanes (PMSSQ)/Si using low-temperature hydrothermal reaction at 80°C for 4 h. The effect of non-annealing and various annealing temperatures, 200°C, 300°C, and 400°C, of the ZnO-seeded template on AuNP size and distribution was systematically studied. Another PMMSQ layer was spin-coated on AuNPs to study the memory properties of organic insulator-embedded AuNPs. Well-distributed and controllable AuNP sizes were successfully grown directly on the substrate, as observed using a field emission scanning electron microscope followed by an elemental analysis study. A phase analysis study confirmed that the ZnO sacrificial template was eliminated during the hydrothermal reaction. The AuNP formation mechanism using this hydrothermal reaction approach was proposed. In this study, the AuNPs were charge-trapped sites and showed excellent memory effects when embedded in PMSSQ. Optimum memory properties of PMMSQ-embedded AuNPs were obtained for AuNPs synthesized on a seeded ZnO template annealed at 300°C, with 54 electrons trapped per AuNP and excellent current–voltage response between an erased and programmed device.

Comprehensive Investigation of Diffuser/Nozzle Element at Low Reynolds Number Aimed at Valveless Pump Design

The performance of diffuser/nozzle element in valveless pumps depends upon a number of geometrical and operational parameters. In this study, the characteristics of low Reynolds number (Re < 100) flow through conical and planar diffuser/nozzle elements with varying half-angle and area ratio (AR) were investigated with simulations and experiments. The optimal half-angle, at which maximum diffuser efficiency occurs, was found to decrease with Reynolds number for both conical and planar elements. Therefore, the results provide a selection criterion for a diffuser/nozzle pair in a valveless micropump design, where no such criterion is available so far.

Comparative Study of Copper Diffusion in Plasma Treated Low-k Dielectric Thin Film Using XPS and SIMS

Low-k dielectric improves the switching speed by reducing the parasitic capacitance in integrated circuits. However it suffers the problem of copper diffusion. Forming gas (H2 + N2) plasma treatment on the surface of HSG-7000 low-k dielectric thin film has demonstrated to improve copper diffusion resistance. Two techniques using X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS) have been used to examine the copper diffusion on this thin film. A thin layer of 10 nm with C-N bonds near the HSG-7000 surface were believed to be created by the plasma treatment and confirmed with XPS and SIMS and acts as barrier.

Low velocity digital air flow sensor from 3D printed PEDOT:PSS micro-hair structures

This paper reports a novel method for digital sensing of low-velocity air flow using high aspect-ratio 3D printed conducting polymer (PEDOT:PSS) micro-hair structures (1000 μm long, 5.5±0.5 μm diameter). By implementing multiple micro-hair structures as micro-switches that respond to air flows of particular velocities, a low-velocity digital flow sensor capable of detecting air flow in the range of 61 mm/s to 99 mm/s is demonstrated.

EFFECT OF ZINC NITRATE CONCENTRATION ON FORMATION OF AuNPs BY SACRIFICIAL TEMPLATED GROWTH HYDROTHERMAL APPROACH AND ITS PROPERTIES IN ORGANIC MEMORY DEVICE

This paper describes a novel fabrication technique to grow gold nanoparticles (AuNPs) by using the sacrificial templated growth hydrothermal reaction approach. The effect of zinc nitrate Zn (NO3)2 concentration in the hydrothermal reaction on the formation of AuNPs was studied by varying the concentration from 0.01 M, 0.05 M, 0.1 M and 0.2 M. The increase of Zn (NO3)2 concentration lead to formation of smaller size and lower area density of AuNPs. XRD analysis proved the formation of AuNPs by using this approach. From scanning electron microscope images, the sample with 0.1M of Zn (NO3)2 concentration showed better AuNPs distribution. In order to investigate the memory properties of AuNPs embedded in organic insulator, polymethylsilsesquioxane (PMSSQ) was spin coated as insulator layer between the AuNPs. I-V and C-V characteristics showed hysteresis properties that indicated charge storage capability of AuNPs embedded organic insulator. AuNPs grown on 300°C annealed ZnO template in 0.1M of Zn (NO3)2 hydrothermal bath produced the best memory properties whereby 54 of electron charges has been stored per AuNPs in C-V measurement.