SFB 292: project A6 (Silicides)

project description

Transition metal silicides show a phase diagram rich in crystal structures and crystal stoichiometries. Furthermore it is possible to grow layer structures on silicium substrate, which are not stable as volume crystals. Due to this plenitude of different phases the silicides show a broud spectrum of material characteristics important for applications, such as metallic conductivity, magnetism or semimetallic behaviour. Silicides are especially interesting because of their compatibility to silicium technology. In the scope of the project at hand we examined the volume- and surface-properies of silicide layers with ab initio methods.
We were able to predict the crystallographic, elastic and electronic properties for platinum silicides and iridium silicides. These predictions directly complement experiments performed with layers, whose volume structure was metastable. For example an IrSi2-phase in a CaF2-structure was observed in an experiment in the special research division. The theoretical calculations helped to ensure the characterisation, that was difficult due to the small layer thickness. We investigated the termination and layer relaxation of ferromonosilicide-layers and their electronic structure in collaboration with experimental projects. These questions are relevant for the growth and characterisation of the metastable layers. We were able to trace a layer relaxation,which was unusual for typical metals, back to a covalent bond type of the iron-silicium- and the iron-iron-bonds. Similar bond properties have been found for all low index plains. The trends, that we found during the analysis of the bond proportions, the layer relaxations and the work function, are also interesting with regard to the discussion of aluminium surface properties, which differ from the common idea of Smouluchoski smoothening.

project data
project dataProf. Dr. Oleg Pankratov
participantsDr. Michel Bockstedte, Dr. John Klepeis
keywordssilicides, coating
duration1998-01-01 - 2001-12-31
sponsorsGerman Research Foundation
contactphone +49 9131 8528824
fax +49 9131 8528833
e-mail: oleg.pankratov@physik.uni-erlangen.de

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