First principles study of the atomic layer deposition of alumina by TMA-H2O-process

Atomic layer deposition (ALD) is a coating technology used to produce highly uniform thin films. Aluminiumoxide, Al2O3, is mainly deposited using trimethylaluminium (TMA) and water as precursors and is the most studied ALD-process to date. However, only few theoretical studies have been reported in the literature. The surface reaction mechanisms and energetics previously reported focus on a gibbsite-like surface model but a more realistic description of the surface can be achieved when the hydroxylation of the surface is taken into account using dissociatively adsorbed water molecules. The adsorbed water changes the structure of the surface and reaction energetics change considerably when compared to previously studied surface model. Here we have studied the TMA/H2O process using density functional theory on a hydroxylated alumina surface and reproduced the previous results for comparison. Mechanisms and energetics during both the TMA and the subsequent water pulse are presented. TMA is found to adsorb exothermically onto the surface. The reaction barriers for the ligand-exchange reactions between the TMA and the surface hydroxyl groups were found to be much lower compared to previously presented results. TMA dissociation on the surface is predicted to saturate at monomethylaluminium. Barriers for proton diffusion between surface sites are observed to be low. TMA adsorption was also found to be cooperative with the formation of methyl bridges between the adsorbants. The water pulse was studied using single water molecules reacting with the DMA and MMA surface species. Barriers for these reactions were found to reasonable in the process conditions. However, stabilizing interactions amongst water molecules were found to lower the reaction barriers and the dynamical nature of water is predicted to be of importance. It is expected that these calculations can only set an upper limit for the barriers during the water pulse.Peer reviewe

Noctua janthina and N. janthe (Lepidoptera, Noctuidae) in Finland

Of the 15 reported Finnish finds of Noctua janthe (Borkhausen,ll92) one proved fobe N. janthina (Denis & Schiffermüllet, 1775), which is now for the first time recorded from Finland. The two species are compared, and their distribution in Finland recorded

Consistency of multidimensional combinatorial substitutions

Multidimensional combinatorial substitutions are rules that replace symbols by finite patterns of symbols in $\mathbb Z^d$. We focus on the case where the patterns are not necessarily rectangular, which requires a specific description of the way they are glued together in the image by a substitution. Two problems can arise when defining a substitution in such a way: it can fail to be consistent, and the patterns in an image by the substitution might overlap. We prove that it is undecidable whether a two-dimensional substitution is consistent or overlapping, and we provide practical algorithms to decide these properties in some particular cases.Comment: 13 pages, v2 includes corrections to match the published versio

Notes on the scythridid fauna of the Altai Mountains, with description of four new species (Lepidoptera: Scythrididae)

A list of 16 species embracing 393 specimens of the family Scythrididae collected during 23.VI.–11.VII.2000 from the Altai Mountains is presented. Four new species are described: Scythris cervella sp. n., S. hamatella sp. n., S. spinella sp. n. and S. tumidella sp. n. In addition, S. felixi Bengtsson & Sutter, 1996 is reported as new for Russia and seven more species as new for the Altai region. The known distribution range of each species is given as well as further notes on some poorly known taxa

Pterophorus poculidactyla sp. n. from the Altai Mountains (Lepidoptera: Pterophoridae)

Pterophorus poculidactyla sp. n. is described from the Altai Mountains. Two male specimens were collected by net in late June 2000 on an alpine meadow at an elevation of 2500 m. The new taxon is a close relative to P. volgensis (Möschler, 1862) and P. taklamakanus (Arenberger, 1995) but differs from both these species externally and by details in the male genitalia

Scythris saarelai sp. n. from southern Spain and further records of Scythris mariannae Bengtsson, 1991 with a new synonym (Lepidoptera: Scythrididae)

Scythris saarelai sp. n. is described from southern Spain. Three males and two females were collected by net in late March and early April 1998 on hot, dry slopes in two different localities. The small, dark moth is difficult to separate from many other scythridids without examining the genitalia. Three further specimens (2 ♂♂, 1 ♀) of Scythris mariannae Bengtsson, 1991, a species previously known only by the male holotype, were found in Spain, prov. Malaga. The external appearance of these specimens differs from the habitus of the holotype. However, the male genitalia are identical. The examination of the female genitalia was showed that Scythris annae Bengtsson, 1997 syn. n. is a junior synonym of S. mariannae

Greenhouse gas balance of forestry-drained boreal peatlands: Sinks or sources?

Non peer reviewe