Key Engineering Materials Vol. 945

Abstract: The effects of modification, electromagnetic stirring and compound treatment (modification and electromagnetic stirring) on the microstructure and thermal stability of Al-13% Si alloy are experimentally investigated. The results show that the three melt treatments can change the microstructure of the alloy. The modification has obvious refining effect on primary silicon and eutectic silicon grains, electromagnetic stirring has refining effect on primary silicon grains, and eutectic silicon grains appear coarsening phenomenon. The latent heat is obviously decreased by electromagnetic stirring, while the latent heat is increased by modification. Refining eutectic silicon grains will increase the latent heat of phase transformation of the alloy. When 560 °C remains unchanged, the melting temperature of the alloy generally decreases with the increase of holding time, but fluctuates, with a decrease of 7 °C. The latent heat decreases with the increase of constant temperature time, and the decrease amplitude reaches 8.4%.

Abstract: The present work reviews the results of the photoluminescence (PL) study of silver-doped ZnO nanostructures synthesized by both physical and chemical methods. ZnO is a semiconductor with a binding energy of 60 meV, which ensures efficient near-band-edge band emission at a temperature of 300K and ultraviolet emission of bulk ZnO, and ZnO has a bandgap energy of 3.37 eV at room temperature. By tuning the growth process parameters of silver-doped ZnO nanostructures, the optical properties of ZnO can be controlled for use in various optoelectronic components, biosensors, blue-emitting diodes, and even white light sensors.

Abstract: Ti15Mo7Zr15Ta1.00Si titanium alloy contained higher concentration of silicon and better elastic properties, excellent biocompatibility and lower processing cost. To investigate the influence of texture shapes and parameters of joint surfaces on the friction and wear properties under bionic lubrication conditions, three types of texture morphologies (circular, elliptical, and equal-width grating) with the same pit depth and surface coating rate were processed on a Ti15Mo7Zr15Ta1.00Si titanium alloy using a picosecond laser processing system in this study. Then, the "ceramic–metal" friction and wear tests of textured and smooth samples under lubrication with bovine serum protein were performed using a UMT-3 multifunctional friction and wear testing machine. The results showed that the surface micro-texture morphology could improve the anti-friction properties of titanium alloy artificial joint materials. The wear resistance of the circular micro-dimples improved with an increase in the circular diameter. In the elliptical micro-dimple texture morphology, the vertical arrangement of the ellipses could provide the maximum bearing capacity and best friction reduction effect, followed by the elliptical morphology and the transverse ellipse arrangement. The denser the arrangement of the equal-width bars, the better the friction reduction effect was.

Abstract: Alginate is natural biodegradable polymers often used for wound treatments and drug delivery purposes. Due to thestructural characteristics, alginate polymers are able to form hydrogel. Alginate nanoparticles are obtained by diverse methodologies and the physical and chemical properties can be affected by production techniques and the molecules incorporated. Alginate possesses unique bioactivities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity, so it has great potential for biomedical applications. Alginate based hydrogels and nanoparticles carrying active compounds are able to supply the optimal environments for wound healing and controlled drug administration including targeted or localized drug-delivery systems. In this review, the recent researches about the alginate and alginate-complex nanoparticles as potential tools for wound dressing membrane and drug delivery carriers are studied.

Abstract: Inkjet printing is a promising technique for fabricating printed electronics. This technique acquires the utilization of conductive ink to form a fine and thin resolution conductive structure on a flexible substrate. The challenges are to design a stable conductive ink with a controlled properties to prevent nozzle clogging. Furthermore, a fine structure construction often demonstrated poor device performance due low mechanical durability. In this work, we have characterized morphology of the newly developed inkjet-printable nanosilver conductive ink (Mi-Ag) in our laboratory. The ink shows a stable colloidal ink zeta potential of-79.1 mV with nanoparticle size less than 100 nm properties has been tailored for compatibility with inkjet printing of conductive pattern on polyethylene terephthalate (PET) flexible substrate. It has been ascertained that the flexible electronic form factor affects the quality of the physical and electrical properties of printed pattern and the device performance. Hence, the bending test of the printed RFID patterns fabricated with different layer of thicknesses was investigated. Electrical properties of the samples were monitored by in-situ conductivity and resistivity measurement under cyclic bending testing. Pattern with thinnest layer of 1.31μm (1X) had the smallest electrical properties percentage drop (38.4%) at 12,000 bending cycles due to the fact that in thick layer, the interparticle network started to change during bending and became weaker due to the large amount of the particles in the dense printed layer. In contrast, printed device exhibited minimal increase in resistivity. Consequently the particle gap increased which allowed the movement of electrons, leading to the increased of electrical resistance. The device endurance characteristic is crucial to satisfy future design requirement of flexible electronic applications.

Abstract: SRAM (Static Random Access Memory) is an essential component of memory devices such as laptops, phones, etc., which act as a semiconductor memory. The “Carbon Nanotube Field Effect Transistor (CNTFET)” is silicon associated high-stability, low-power device with excellent performance. CNTFET has been verified to be very advantageous for Very large-scale integration circuit designs in the nanoscale range because of its remarkable properties of metal oxide semiconductor field effect transistor (MOSFET). The material was brought to light because of its genuinely incredible electrochemical performance. Carbon nanotubes have unique properties such as high charge carrier mobility, high voltage, small footprint, exceptionally short and high control over pulse duration, and large current densities. In traditional MOSFET, bulk silicon is used, which has high leakage current and high field-effect; thus, CNTFET has been used as an alternative in recent years. When compared to the 10T CNTFET SRAM Bit cell is designed using HSPICE Tool in 22nm technology. Long-term stability and significant process variable changes are significant challenges with nanoscale SRAM cells.

Abstract: Due to the challenging dispersion of graphene in aqueous media, organic solvents are commonly used in conductive graphene inks. This will result in safety issues and environmental pollution. In this study, we demonstrated a green approach of graphene ink preparation through one-pot synthesis reaction that produce a hybrid reduced graphene oxide (rGO)-silver nanoparticles (AgNPs), with deionized water as solvent. The synthesized rGO-AgNPs was monitored using ultraviolet–visible (UV-Vis) spectroscopy and fourier transform infrared (FTIR). A stable dispersion of rGO-AgNPs ink was confirmed through UV-Vis analysis. FTIR result showed the removal and the reduction in the intensities of absorption bands of oxygen-containing functional groups, which indicated that graphene oxide (GO) has been successfully reduced to rGO in the hybrid ink. The printed film of rGO-AgNPs exhibited a high conductivity of 1.50 × 10⁴ S/cm, proven that the electrical performance of the hybrid ink has been improved as compared to previously reported GO-based ink. Printed into interdigitated electrode (IDE), the impressive characteristic of our hybrid ink performed well as a high-sensitivity flexible humidity sensor.

Abstract: In this paper, the modeling of SJ-MOSFETs beyond the voltage class of 3.3 kV simulated with verified deep aluminum box-like shaped profiles by using TCAD simulation is described. The simulation results are used to investigate the influence of ion implantation parameters on electrical characteristics. For the formation of pillar regions, high energy implantation is performed through energy filter with a multi epitaxial growth method using a patterned mask. While high thickness of epitaxial layer is indispensable for obtaining a high blocking capability, it is revealed that the optimization of doping concentration of p-pillar and drift layer parameters yields similar on-state-resistance by charge compensations of SJ-structure.

Abstract: We demonstrate quasi-vertical GaN MOSFETs fabricated on SiC substrates. The GaN epitaxial layers were grown via MOCVD on 100 mm 4H-SiC wafers, with the device structure consisting of a 2.5 μm drift layer and a Mg doped p-GaN body. The fabricated transistors exhibit normally-off characteristics, with low off-state leakage behavior and an on/off ratio of over . The specific on-resistance was measured to be which compares favorably to devices fabricated on other foreign substrates. Our results demonstrate an alternative substrate for realizing vertical GaN devices, which potentially offers better material quality and thermal properties compared with other foreign substrate choices.