Atomic Structures of Two-Dimensional Strained InAs Epitaxial Layers on a GaAs(001) Surface: in situ Observation of Quantum Dot Growth

摘要

Scanning tunneling microscopy and reflection high-energy electron diffraction under ultrahigh vacuum conditions were used to make an in situ study of atomic structures at the surface of an InAs/GaAs hetero-structure grown by molecular-beam epitaxy. It was observed that the deposition of approximately 0.3 ML of indium on an arsenic-enriched GaAs(001) -2 * 4 surface leads to the formation of the 4 * 2 phase while the deposition of 0.6 ML indium leads to the appearance of a new 6 * 2 reconstruction. It is shown that layer-by-layer two-dimensional epitaxial growth of InAs on GaAs(001) as far as 13 monolayers can only be achieved if the growth front reproduces the 4 * 2 or 6 * 2 symmetry of the substrate and models of 4 * 2 and 6 * 2 reconstructions are proposed. Atomic-resolution images of faceted planes on the surface of three-dimensional islands in an InAs/GaAs(001) system were obtained for the first time and structural models of these were developed.