Growth and overgrowth of huts and domes in the InAs/GaAs(001) system
Abstract
InAs/GaAs(001) quantum dots (QDs) are grown at high temperature and extremely low flux and analyzed by in-situ scanning tunneling microscopy. A bimodal distribution of dots is measured, composed of ?small? and ? large? islands. By a precise analysis of their shapes and facet orientation we are able to identify a striking similarity with the Ge/Si(001) system. The large dots (domes) are multifaceted and mainly characterized by steep (101) and (111) facets but show also shallow (137) facets at the top and the foot. Small dots (huts) are only characterized by shallow (137) facets. The experimental findings are in excellent agreement with recent theoretical predictions of the equilibrium crystal shape of InAs quantum dots. The GaAs overgrowth of these QDs is investigated during the initial stages. Two regimes appear to dominate the capping, an initial partial dissolution of the QDs followed by a true overgrowth. The first regime is driven by the In/Ga intermixing that causes a reduction of the extension of the steeper facets and an increase of the shallower ones. Also in this case a close similarity can be found with the Ge/Si(001) case. While the first regime is flux-independent, the second one is strongly influenced by kinetic effects and is governed by different atomic processes.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARU33002C