We use dimeric arsenic (As2) or tetrameric arsenic (As4) during molecular beam epitaxy to manipulate the structural and optical properties of GaAs(111)A tensile-strained quantum dots (TSQDs). Choice of arsenic species affects nucleation and growth behavior during TSQD self-assembly. Previously, epitaxial GaAs(111)A TSQDs have been grown with As4, producing TSQDs with a triangular base, and 'A-step' edges perpendicular to the three 1̅1̅2 directions. We demonstrate that using As2 at low substrate temperature also results in triangular GaAs(111)A TSQDs, but with 'B-step' edges perpendicular to the three 112̅ directions. We can therefore invert the crystallographic orientation of these triangular nanostructures, simply by switching between As4 and As2. At higher substrate temperatures, GaAs(111)A TSQDs grown under As2 develop with a hexagonal base. Compared with triangular dots, the higher symmetry of hexagonal TSQDs may reduce fine-structure splitting on this (111) surface, a requirement for robust photon entanglement. Regardless of shape, GaAs(111)A TSQDs grown under As2 exhibit superior optical quality.
This is the Accepted Manuscript version of an article accepted for publication in Semiconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6641/aba6e0
Schuck, Christopher F.; Vallejo, Kevin D.; Garrett, Trent; Yuan, Qing; Wang, Ying; Liang, Baolai; and Simmonds, Paul J.. (2020). "Impact of Arsenic Species on Self-Assembly of Triangular and Hexagonal Tensile-Strained GaAs(111)A Quantum Dots". Semiconductor Science and Technology, 35(10), 105001. https://doi.org/10.1088/1361-6641/aba6e0