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.
Highlights
Quantum dots (QDs) can be formed by growing InAs on GaAs by molecular beam epitaxy (MBE) in the StranskiKrastanov growth mode [1,2,3,4,5,6]
We investigated the influence of the size, aspect ratio, and depth of the nucleation site on quantum dot nucleation
The occupation increases with increasing aspect ratio, where the QDs align along a chain in the elongated direction
Summary
Quantum dots (QDs) can be formed by growing InAs on GaAs by molecular beam epitaxy (MBE) in the StranskiKrastanov growth mode [1,2,3,4,5,6]. The finite lattice mismatch between the two materials leads to the formation of nanometer-scaled InAs islands which, if covered with GaAs, act as QDs due to the lower bandgap of InAs [7,8]. These QDs show unique properties which make them interesting for many applications like single photon sources [9,10,11,12,13]. In a microcavity, the QDs have to be placed exactly at the mode positions of photonic cavities in order to maximize coupling and device performance [13]. The deformation of surface chemical potential leads to accumulation of In
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