Thermal chemical vapor deposition at temperatures as low as 423 K, using Ru3(CO)12 with no accompanying reactive gas, forms pure, uniform, and smooth Ru films on Ta and low-resistivity films on SiO2. A 2.5-nm-thick Ru film fully covers the underlying Ta and the Ru film is thermally stable up to 573 K. Unlike Ta, Ru films exhibit excellent wetting by Cu even when the Ru surface is contaminated with small amounts of oxygen.

Search engines largely rely on Web robots to collect information from the Web. Due to the unregulated open-access nature of the Web, robot activities are extremely diverse. Such crawling activities can be regulated from the server side by deploying the Robots Exclusion Protocol in a file called robots.txt. Although it is not an enforcement standard, ethical robots (and many commercial) will follow the rules specified in robots.txt. With our focused crawler, we investigate 7,593 websites from education, government, news, and business domains. Five crawls have been conducted in succession to study the temporal changes. Through statistical analysis of the data, we present a survey of the usage of Web robots rules at the Web scale. The results also show that the usage of robots.txt has increased over time. General TermsExperimentation, Measurement.

In this study, a highly soluble PCBM-based thermo-cross-linkable fullerene precursor has been synthesized for use in bulk heterojunction based organic solar cells. The cross-linking was achieved using a thermally activated benzocyclobutene (BCB) molecule. The thermo-crosslinking reaction is initiated at temperatures as low as 150 C. Compared to PCBM, the cross-linked fullerene is highly insoluble and has a diffusional mobility in poly(3-hexylthiophene) (P3HT) that is an order of magnitude slower than PCBM. Its electron mobility is comparable to that of PCBM and organic photovoltaic (OPV) devices consisting of bulk heterojunction active layers with P3HT or PTB7 and this fullerene show very similar efficiencies. Devices prepared either with pure cross-linked fullerene or its mixture with PCBM as acceptors in OPVs have been shown to be highly stable to accelerated aging with little loss in device efficiency up to 48 hours of aging at 150 C. This compares to a loss of 60% of initial efficiency in identically prepared devices when using PCBM as the acceptor. Optical microscopy and grazing incidence wide angle X-ray scattering (GIWAXS) shows that a probable cause for this excellent stability in the cross-linked fullerene containing BHJs is associated with a significant inhibition of formation of crystals of fullerene.

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