The importance of high-index surfaces for the morphology of GaAs quantum dots

Abstract

Results of a combined experimental and theoretical study are presented. GaAs{113} and {112} surfaces have been prepared by molecular beam epitaxy and analyzed in situ by low-energy electron diffraction and ex situ by atomic-force microscopy. The experimentally found structures are in full agreement with surface energies calculated by density-functional theory. The {112} surfaces are unstable under faceting into low-index planes, whereas the {113} surfaces appear as singular surfaces. Particularly, for GaAs(113) the surface energy is comparable with the values for the low-index surfaces. The impacts of these results on the interface between InAs quantum dots and the embedding GaAs matrix are discussed.

Crystal shape of GaAs nanocrystals deposited on Si(100) by molecular beam epitaxy

“…In the Wulff's theory, the ratio of the surface energy of facets to the distance between the Wulff point and the facets is constant when a crystal forms equilibrium crystal shape in order to minimize the total surface energy of the crystal. The surface energy of {311} facets is as low as that of {111} facets in GaAs crystal [16]. Therefore, the dome crystal consisted of {111} and {311} facets is nearly equivalent to a part of equilibrium crystal shape constructed under the Wulff theory.…”

Au impact on GaAs epitaxial growth on GaAs (111)B substrates in molecular beam epitaxy

“…According to crystallography of the zinc-blende structure, {113} B facets have relatively low surface energy under As-rich environment. 35 In the case of growing aggregated GaAs on {111} B surface epitaxially, formation of {113} B surface facets is then thermodynamically preferred, in which the Ga source comes only from the Ga surface diffusion. For the {111} B surface, 3 possible equivalent {113} B surface facets formed as triangular pyramids.…”

Molecular-beam epitaxial growth and surface characterization of GaAs(311)B

“…The observation is in sharp contradiction to that of other authors from low-energy electron diffraction ͑LEED͒ and photoelectron spectroscopy studies resulting in the statement that the GaAs͑311͒B surface is not stable and does not show any superstructure even after preparation by MBE. 10 Theoretical investigations for GaAs͑311͒B by Platen et al 15 do not consider a superstructure. Our STM experiments, however, confirm the results obtained by RHEED.…”