Effects ofin situannealing of GaAs(100) substrates on the subsequent growth of InAs quantum dots by molecular beam epitaxy

Abstract

In the present work, we study the growth by molecular beam epitaxy of InAs self-assembling quantum dots (SAQDs) on GaAs(100) substrates subjected to an in situ annealing treatment. The annealing process consists of the exposition of the GaAs buffer layer surface to high temperatures for a few seconds with the shutter of an arsenic Knudsen cell closed. The purpose of the annealing is to obtain a better uniformity of the SAQD sizes. In our study we prepared different samples using the Stranski-Krastanov growth method to obtain InAs/GaAs(100) quantum dot samples with different annealing times and temperatures. Their structural and optical properties were studied by reflection high-energy electron diffraction (RHEED), high-resolution scanning electron microscopy (HRSEM), atomic force microscopy (AFM), and photoreflectance spectroscopy (PR). According to the results of AFM and HRSEM, by the thermal treatment we obtained a better distribution of quantum dot sizes in comparison with a reference sample with no treatment. The PR spectra from 0.9 to 1.35 eV presented two transitions associated with SAQDs. The energy transitions were obtained by fitting the PR spectra using the third derivative model.

Tuning the properties of exciton complexes in self-assembled GaSb/GaAs quantum rings

“…Sample A has larger dots of lower density than sample B (see Table I), most likely a result of the difference in the GaAs grown at different temperatures. 12 However, the point to emphasize here is that in both cases, the surface GaSb nanostructures appear entirely dotlike.…”