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Ge-Quantum Dots on SI(001) Tailored by Carbon Predeposition
Published online by Cambridge University Press: 10 February 2011
Abstract
The morphology of Si(001) after carbon deposition of 0.05 to 0.11 monolayers (ML) was investigated in situ by ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The carbon induces a c(4×4)-reconstruction of the surface. In addition, carbon increases the surface roughness compared to clean Si(001) (2×1). In a second step, the influence of the carbon induced restructuring on Ge-island nucleation was investigated. The 3D-growth sets in at considerably lower Ge coverage compared to the clean Si(001) (2×1) surface. This leads to a high density of small though irregularly shaped dots, consisting of stepped terraces, already at 2.5 ML Ge. Increasing the Ge-coverage beyond the critical thickness for facet formation, the dots show { 105 }- facets well known from Ge-clusters on bare Si(001) (2×1). However, they are flat on top with a (001)-facet showing the typical buckled Ge rows and missing dimers. This indicates that the compressive strain is not fully relaxed in these hut clusters.
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- Copyright © Materials Research Society 1998
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