Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 32: Epitaxie und Wachstum II
O 32.10: Vortrag
Donnerstag, 27. März 2003, 17:15–17:30, FOE/ANOR
Surfactant mediated growth of Ge-films on (111) Si - Microstructural analysis of defects and strain — •Roland Kröger1, Thomas Schmidt1, Peter L. Ryder1, Jens Falta1, Andreas Janzen2, and Michael Horn-von Hoegen2 — 1Institut für Festkörperphysik, Universität Bremen, 28359 Bremen — 2Institut für Laser- und Plasmaphysik, Universität Essen, 45117 Essen
Ge films grown on (111) Si are of eminent interest for the realization of microelectronic devices and have entered commercial applications already. However, the realization of thin films with high quality, namely a low defect density and a controlled strain remains an important issue. Using a surfactant, in our case Sb, allows to significantly improve film properties. A microstructural analysis of these films was performed using transmission electron microscopy (TEM) for Ge films, which were grown under different deposition temperatures (in the range of 450∘C to 650∘C) by molecular beam epitaxy (MBE) resulting in a layer thickness of about 5 to 10 nm. The films were studied using high resolution TEM in plan view and cross section. The average distance of misfit dislocations determined from Fourier transformed and filtered cross sectional HRTEM images and the assessment of Moiré patterns formed by the superposition of the Ge and Si lattices reveal the increase of ordering with temperature and thus the increased relaxation of the films. Based on the quantitative evaluation of the findings the strain development and defect formation is discussed.