Open Access Nano Express

Influence of hole shape/size on the growth of site-selective quantum dots

Christian J Mayer1*, Mathieu F Helfrich2 and Daniel M Schaadt1

Author Affiliations

1 Institute for Energy Research and Physical Technologies, Clausthal Technical University, Am Stollen 19B, Goslar 38640, Germany

2 DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, Karlsruhe 76131, Germany

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Nanoscale Research Letters 2013, 8:504  doi:10.1186/1556-276X-8-504

Published: 1 December 2013

Abstract

The number of quantum dots which nucleate at a certain place has to be controllable for device integration. It was shown that the number of quantum dots per nucleation site depends on the size of the hole in the substrate, but other dimensions of the nucleation site are vague. We report on the influence of hole shape on site-selectively grown InAs quantum dots (QDs) by molecular beam epitaxy. Dry etching of the GaAs wafers was used because of its high anisotropic etching characteristic. Therefore, it was possible to verify the influence of several hole shape parameters on the subsequent QD growth independently. We show that the nucleation of these QDs depends on several properties of the hole, namely its surface area, aspect ratio of the surface area, and depth. Especially, the aspect ratio shows a big influence on the number of nucleating QDs per site. With knowledge of these dependencies, it is possible to influence the number of QDs per site and also its distribution.

Keywords:
Molecular beam epitaxy; MBE; QD; Quantum dot; InAs; Site selective; Lithography; Dry etching; ICP