Properties of self-assembled Ge islands grown by molecular beam epitaxy. (14th April 2009)

• Record Type: Journal Article
• Authors: Ray, Samit K.; Singha, Rajkumar; Das, Samaresh; Das, Kaustuv; , Achintya Dhar
• Is Part Of: International journal of nanotechnology. Volume 6:Number 5/6(2009)
• Page Start: 552
• Page End: 566
• Publication Date: 2009-04-14
• Subjects: self-assembly -- MBE -- Ge islands -- heterostructures -- germanium islands -- nanotechnology -- molecular beam epitaxy -- annealing -- stability -- coarsening; 620.505
• Languages: English
• ISSNs: 1475-7435

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.