ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity

Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications

Intrinsic MOSFET leakage of high-k peripheral DRAM devices: Measurement and simulation

The gate leakage (I Gate, table 1) is reduced compared to the conventional 65nm process with SiON dielectric (Fig. 2). The leakage current due to direct tunneling is simulated using the CET as fitting parameter. High-k PFETs with an oxide extension spacer show a decrease in leakage density with reducing channel length, due to an average CET increase of 1Å (Fig. 3). Most likely unintended oxidation of the interlayer at the gate edge by oxygen supply through the spacer causes the CET increase (Fig. 1). The phenomenon is avoided using a nitride extension spacer. But nitride spacers at the inner gate edge are known to lead to increased gate induced drain leakage (GIDL) [8]. A dual oxide nitride extension spacer is sufficient to prevent unintended gate edge oxidation (Fig. 3)

Dielectric backside passivation - improvements by dipole optimization

Based on an examination of interface effects on negative fixed charge formation in Al2O3 we have been able to attribute the charge centroid to the oxide interface between Al2O3 and SiO2. The formation of negative fixed charge seems strongly related to the presence of oriented Al-O-Si bonds, which induce a dipole, causing the negative charge. Improvement of back side passivation should therefore focus on SiO2 interface optimization

Congenital myasthenic syndromes in two kinships with end-plate acetylcholine receptor and utrophin deficiency

We studied two families with five affected members suffering from ptosis and slowly progressive limb-girdle muscle weakness. All patients had abnormal decremental response on low-frequency nerve stimulation, but there were no repetitive responses to single stimuli. The patients improved on anti-acetylcholinesterase drugs. Intercostal muscle was obtained for special studies from one patient of each family. In vitro microelectrode studies were done in Patient 1. Miniature end-plate potentials were of low amplitude, and the quantal content of the evoked end-plate potentials was normal. Light microscopy revealed a marked type 1 fiber predominance. Acetylcholinesterase reactivity was dispersed over increased length of individual fibers in Patient 2. On morphometry of the end-plate ultrastructure, the number of secondary synaptic clefts per neuromuscular junction and the expansion of the postsynaptic area were markedly reduced. In Patient 1, but not in Patient 2, the envelopment of the nerve terminal by Schwann cell was increased. Acetylcholine-receptor (AChR) density was reduced as judged by the reduced immunoreactivity to antibodies against different receptor subunits. Immunohistochemical analysis of proteins known to be involved in orchestrating the end-plate structure showed deficiency of the AChR-associated protein utrophin. These patients appear to have a defect in the development or maintenance of the postsynaptic clefts; whether this defect results from or causes a reduced expression of utrophin or AChR is unclear