Ab initio density functional theory and ballistic transport theory are applied to the calculation of tunneling current through ultra-thin SiO2 gate dielectrics. The Si/SiO2/Si model interface has been constructed by orienting a crystalline SiO2 (β−cristobalite) slab such that the misfit with Si (001) was minimized and no dangling bonds appear at the interface. The structure was then sandwiched ...

Nafion polyelectrolyte is widely used in polymer electrolyte membrane fuel cells (PEMFC) due to its high proton conductivity. The properties of hydrated Nafion are attributed to its nanophase-segregated structure in which hydrophilic clusters are embedded in a hydrophobic matrix. However, there has been little characterization of how the monomeric sequence of the Nafion chain affects the nanoph...

Changes in the optical absorption and the formation of point defects in three types of synthetic SiO2 glasses, wet ~OH content; 120 ppm!, dry ~OH content ,1 ppm!, and fluorine ~F!-doped ~;1 mol %! SiO2 glasses, by irradiation with fluorine dimer (F2) excimer laser light pulses (;8 mJ/cm / pulse33.6310 pulses) were examined by various spectroscopic methods. Intense optical absorptions were induc...

We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membran...

Nafion contamination by ferrous-alloy corrosion products, resulting in dramatic drops of the Ohmic potential, is a suspected major failure mode of polymer electrolyte membrane fuel cells that make use of metallic bipolar plates. This study demonstrates the potential of scanning transmission X-ray microscopy combined with X-ray absorption and fluorescence microspectroscopy for exploring corrosio...

polyacrylonitril (pan)-supported chitosan (cs) nanocomposite membranes were prepared by cross-linking the cs with 3-aminopropyl-triethoxysilane (apteos) via sol-gel method. pervaporative performances of the cs-sio2/pan membrane for dehydration of aqueous alcohol solutions were investigated. from sem cross-sectional images of the membrane, the spongy pores and the finger-like pores were found in...

Palladium doped silica membranes were synthesized by the sol-gel method using two different procedures. The first palladium-doped silica membrane (M1) was synthesized with a coating of four layers of silica-palladium sol. The second membrane (M2) was synthesized with a coating of two silica layers followed by a coating of two silica-palladium layers. Scanning electron microscopy (SEM) proved th...

In this thesis, Er doped SiO2/nc-Si multilayer structure a promising material for on-chip silicon light emission devices, is studied in detail. It is demonstrated, for the first time, that infrared Er emission could be enhanced by an Er doped SiO2/nc-Si multilayer structure. It is also determined that energy transfer from nc-Si to nearby Er ions, is responsible for this emission enhancement. Th...

Superhydrophobic poly(vinylidene fluoride) PVDF-SiO2 composite membranes with different % of SiO2 contents were prepared by electrospinning. The surface morphologies of the membranes are characterized by using scanning electron microscopy. The nanofibers in the membranes were stacked in layers to produce fully interconnected pores that resulted in high porosity. The incorporation of SiO2 into t...