High-barrier Al/p-Si Schottky diodes
Sequential implantation of argon ions and low-energy hydrogen ions has been found to yield Schottky barriers of exceptionally high values on p-type silicon. The interaction of these ions in Si is quite complex, involving donor defect generation, defect passivation, and acceptor dopant neutralization. The apparent synergism of these specific implants has resulted in Al/p-Si Schottky diodes with an effective barrier height as high as 0.83 eV, among the highest value reported for any metal/p-Si contact.
Interpretation of forward bias behavior of Schottky barriers
Forward bias current flow behavior of Schottky barriers provides important information about the contact through the saturation current and ideality factor. These parameters are usually determined by graphically determining the linear region of a plot of log I against V. This method is subject to the difficulty of determining a linear region if the contact exhibits any series resistance. However, a method is developed that unambiguously determines the three parameters, saturation current, ideality factor, and series resistance using a method suitable for a microcomputer.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.