Fabrication of ultralow-density quantum dots by droplet etching epitaxy


Isolated single quantum dots (QDs) enable the investigation of quantum-optics phenomena for the application of quantum information technologies. In this work, ultralow-density InAs QDs are grown by combining droplet etching epitaxy and the conventional epitaxy growth mode. An extreme low density of QDs (∼106 cm−2) is realized by creating low-density self-assembled nanoholes with the high temperature droplet etching epitaxy technique and then nanohole-filling. The preferred nucleation of QDs in nanoholes has been explained by a theoretical model. Atomic force microscopy and the photoluminescence technique are used to investigate the morphological and optical properties of the QD samples. By varying In coverages, the size of InAs QDs can be controlled. Moreover, with a thin GaAs cap layer, the position of QDs remains visible on the sample surface. Such a low density and surface signature of QDs make this growth method promising for single QD investigation and single dot device fabrication.

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The authors acknowledge the support of the National Science Foundation of the U.S. (EPSCoR Grant No. OIA-1457888), National Program on Key Basic Research Project (2013CB933301), and National Natural Science Foundation of China (61474015). The authors wish to dedicate this article to the memory of Dr. Jan H. van der Merwe.

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Correspondence to Jiang Wu or Zhiming M. Wang.

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Wu, J., Wang, Z.M., Li, X. et al. Fabrication of ultralow-density quantum dots by droplet etching epitaxy. Journal of Materials Research 32, 4095–4101 (2017). https://doi.org/10.1557/jmr.2017.408

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