Abstract

MENDEZ-GARCIA, V.H. et al. Effects of in-situ annealing processes of GaAs(100) surfaces on the molecular beam epitaxial growth of InAs quantum dots. Superf. vacío [online]. 2005, vol.18, n.2, pp.1-6. ISSN 1665-3521.

We studied the growth of self-assembled InAs quantum dots (QDs) on GaAs (100) surfaces subjected to an in-situ annealing treatment. The treatment consists in exposing the GaAs buffer layer surface at a high temperature for a few seconds with the As4-shutter closed. The exposure of GaAs at high temperature leads to the formation of nanometric scale pits plus a Ga-rich surface. The annealing modifies in such a way the GaAs surface that the strain mediated transition from two- to three -dimensional InAs growth takes place at a much larger InAs thickness than the obtained under standard conditions. Moreover, the resulting QDs obtained at the equivalent InAs thickness of 3.4 monolayers (MLs) on the annealed GaAs surfaces presented a smaller size dispersion as compared with the conventionally grown QDs. The photoluminescence (PL) emission spectra corresponding to the samples subjected to the in-situ thermal treatment observed a reduction in the full width at half medium (FWHM) and a clear correlation between the dots size increase and the emission peak red-shift. The new-flanged nucleation propitiated by the annealing process was explained in terms of a generation of an intermediated InGaAs thin film created by Ga-clusters on an atomically rough surface and the impinging In atoms.

Keywords : Nanostructures; Quantum dots; Molecular beam epitaxy; Semiconducting III-V materials.