Speaker：Prof. Bernd Jenichen,PDI(Paul-Drude-Institut)
The ferromagnet (FM) Fe3Si forms Schottky contacts with the semiconductors (SC) Ge and GaAs. A triple layer structure FM-SC-FM may therefore be suitable for Schottky barrier tunneling transistors. The structures of the epitaxial Ge and Fe3Si films on GaAs substrates match well to the known structures of their bulk materials. However, when the Fe3Si film is used as a substrate for epitaxial growth of Ge, the influence of the Fe3Si structure on the growing epitaxial Ge film unexpectedly turns out to be stronger and ordering phenomena occur. These ordering phenomena are induced by the epitaxial growth and were not observed in bulk material up to now. First, molecular beam epitaxy was applied to achieve perfect Ge films on top of ferromagnetic Fe3Si layers. Recently, we utilized the method of solid-phase epitaxy of Ge in order to achieve a high crystallinity of the film and superior interface quality. However, the interdiffusion of Fe, Si, and Ge was not entirely prevented during the annealing process. Therefore the Ge film contained some amount of Fe and Si, leading to a shift of the x-ray diffraction (XRD) peak of the Ge(Fe,Si) film and the formation of a superlattice-like structure inside the Ge(Fe,Si) film. The aim of the present work is the investigation of the structure of the thin Ge(Fe,Si) films.
Bernd Jenichen obtained a doctoral degree in Physics at Humboldt University Berlin in 1982. From 1978 till the end of 1991 he was a scientist at the "Zentralinstitut für Elektronenphysik" of the Academy of Science in Berlin. He was one of the inventors of a new double crystal x-ray method compensating for the strain in processed samples [J. Phys. E21(1988)1062]. Since 1992 he is a scientist at the "Paul-Drude-Institut für Festk?rperelektonik”, where he built up the new x-ray laboratory. From 1996 till the end of 2006 he participated in the establishment of the x-ray wiggler-beamline U125/2 KMC and the corresponding MBE experiment at the Berlin synchrotron facility BESSY II [Rev. Sci. Instrum.74(2003)1267]. At present he is investigating epitaxial films by transmission electron microscopy, high resolution x-ray diffractometry, reflectivity and grazing incidence diffraction.