Size and density control of InAs quantum dot ensembles on self-assembled nanostructured templates

摘要

New morphologies of InAs quantum dot ( QD) ensembles forming on self-assembled GaAs nano-holed island templates are demonstrated. Droplet homoepitaxy ( GaAs/GaAs) is used to generate holed nanoscale-sized mounds that appear to elongate along [ 0 1 (1) over bar]. Depending on the InAs monolayer ( ML) coverages, subsequent InAs deposition forms different sizes and shapes of QD ensembles. While we initially observe the formation of the QDs at the hole sites when less InAs is deposited, QDs form around the edges of the mounds with greater InAs deposition. By varying the InAs depositions and growth temperatures, we demonstrate an ability to control the size and density of QDs. The observed decrease in the necessary critical thickness required for the InAs 2D - 3D transition may be due to the higher density of monolayer steps on the sidewalls of the holes and on the edges of the mounds. This hybrid growth approach overcomes some limitations of typical QD growth on planar GaAs surfaces and may find applications in optoelectronics.