Title: Properties of self-assembled Ge islands grown by molecular beam epitaxy

Authors: Samit K. Ray, Rajkumar Singha, Samaresh Das, Kaustuv Das, Achintya Dhar

Addresses: Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India. ' Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India. ' Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India. ' Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India. ' Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302, India

Abstract: Self-assembled germanium islands have been grown on Si (001) substrates using solid source molecular beam epitaxy. A series of annealing experiments have been performed at a temperature 650°C in order to clarify some issues related to island stability and coarsening mechanism. The shape and size distribution of Ge islands as a function of annealing time up to 90 min have been studied through atomic force microscopy. Foot-prints of the annealed and etched islands have demonstrated that the coarsening is dominated by coalescence mechanisms rather than the Ostwald ripening. A detailed Raman characterisation, using optical phonons as efficient probes in analysing self-organised Si1-xGex islands, is reported. The alloy composition has been determined from the Raman intensities. The experimental results are in good agreement with the strain relaxation obtained from X-ray rocking curve and data from AFM topographic images. The generic mechanisms for the growth of self-assembled Ge islands as a function of growth parameters and post-growth treatment are also reviewed.

Keywords: self-assembly; MBE; Ge islands; heterostructures; germanium islands; nanotechnology; molecular beam epitaxy; annealing; stability; coarsening.

DOI: 10.1504/IJNT.2009.024646

International Journal of Nanotechnology, 2009 Vol.6 No.5/6, pp.552 - 566

Published online: 13 Apr 2009 *

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