The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies

Using ab initio density-functional total energy and molecular-dynamics simulations, we study the effects of various forms of nitrogen postdeposition anneal(PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field-effect transistors. We consider the atomic structure and energetics of nitrogen-containing defects which can be formed during PDA in various N-based ambients: N2, N2+, N, NH3, NO, and N2O. We analyze the role of such defects in fixed charge accumulation, electron trapping, and in the growth of the interface SiO2 layer. We find that nitrogen anneal of the oxides leads to an effective immobilization of native defects such as oxygen vacancies and interstitial oxygen ions, which may inhibit the growth of a silica layer. However, nitrogen in any form is unlikely to significantly reduce the fixed charge in the dielectric.Peer reviewe

Development of the Southern Coastal zone of the Eastern Gulf of Finland (from lebyazhye to the St. Petersburg flood protective dam)

In July–September 2004 and April 2005, the specialists of the Department of Marine and Environmental Geology of All-Russian Geological Institute (VSEGEI) conducted field studies of the coastal zone of the Gulf of Finland from thesouthern alignment of the St. Petersburg Flood Protective Dam to Lebyazhye. The basic purpose of the studies is the analysis of coastal zone dynamics. Along the southern coast of the Gulf of Finland from Lebyazhye to the Dam, three different coastal dynamics zones were identified: (1) flat accumulative shore with aquatic plants, (2) erosion zone and (3) zone of modern sand accumulation. Along-shore sand drift in the eastern direction was also determined. Alongside with routine observations, the comparative analysis of space photography images of the study area, carried out during last 20 years, allowed finding out that as a result of intense eastward sand transfer, as mush as 80 metres of sand accumulative bodies have been eroded since 1982 near the village of Izhora. To the west of a small river, a 230-metres long sand split has been formed since 1982

Late-glacial and Holocene palaeoenvironments in the Baltic Sea based on a sedimentary record from the Gdansk Basin

The focus of this study was the 11.55 m long sediment core 303700-7, which was retrieved from the Gdansk Basin during a cruise of RV ‘Poseidon’ within the frame of the Russian–German Project GISEB. The core was analysed for grain size, elemental chemical composition, organic carbon and palynological spectra. The age control was based on palynostratigraphy and 7 radiocarbon datings of bulk sedimentary organic matter. These data provide a high-resolution record of climatic and marine palaeoenvironments in the Gdansk Basin for the last ca. 13 kyr, from the Bølling to late Holocene time. Sedimentation rates were estimated to vary between 0.37 and 1.62 mm yr–1. Major variations in palaeosalinity were estimated from bromine concentrations in the sediment. This method allows the first quantitative reconstruction of palaeosalinity changes in the Baltic Sea, especially profound during the Littorina and Postlittorina periods (middle to late Holocene). In addition, grain size data indicated several Littorina transgressive–regressive stages and a few episodes of increased near-bottom current activity. Our results from the Gdansk Basin are consistent with palaeoceanographic data from other deep basins of the Baltic Sea and provide new insights into the regional Holocene history

A new map of the Neva Bay bottom sediments and technogenic objects under the result of side-scan sonar profiling

In summer 2004, Department of Marine and Environmental Geology of VSEGEI carried out investigations of the Neva Bay bottom surface east of the St. Petersburg Flood Protective Dam using a side-scan sonar system. The main aim of this experimental work was the creation of a new “factographical” map of bottom sediments and different types of technogenic objects. State geological surveys of the Neva Bay bottom were carried out by VSEGEI in 1987–1989. Besides, geoenvironmental investigations were conducted here in 1993–1995 and 2000–2002. As a result, a set of maps of bottom sediments based on hundreds of sampling stations (both cores and grab-sampler) were compiled. Side-scan investigations of 2004 allowed more exact recognition of the bottom sediment distribution. Furthermore, in some places new data permit to suppose that the sedimentary conditions have changed here during the last decades as a result of high technogenic load, including Flood Protective Dam influence. In summer 2004 there were a joint expedition of the VSEGEI and the Geological Survey of Finland (GTK). Altogether 10 sampling stations from the mud accumulation areas were sampled with a use of Niemisto corer. Cores were sliced in 1 cm samples and analyzed in chemistry laboratory of GTK (Finland) – gamma spectrometry for 137Cs, ICP-AES and ICP-MS, whereupon important results about heavy metals concentration and distribution were received