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In this work we explore the first stages of quantum wire (QWR) formation studying the evolution of the growth front for InAs coverages below the critical thickness, c, determined by reflection high energy electron diffraction (RHEED). Our results obtained by in situmeasurement of the accumulated stress evolution during InAs growth on InP(001) show that the relaxation process starts at a certain InAs coverage RRthis ensemble of isolated nanostructures progressively evolves towards QWRs that cover the whole surface for = c. These results allow for a better understanding of the self-assembling process of QWRs and enable the study of the individual properties of InAs/InP self-assembled single quantum wires. [ABSTRACT FROM AUTHOR]

In this work we report on the ability to form low density Ga(As)Sb quantum ring-shaped nanostructures (Q-rings) on GaAs(001) substrates by the droplet epitaxy technique. The Q-rings are formed by crystallization of Ga droplets under antimony flux. After being capped by a GaAs layer, these nanostructures show surface mounding features that are correlated with the buried nanostructures, as demonstrated by TEM analysis, permitting an easy surface location of the optically active Q-rings. [ABSTRACT FROM AUTHOR]

We present growth and optical characterization measurements of single InAs site-controlled quantum dots (SCQDs) grown by molecular beam epitaxy on GaAs (001) patterned substrates by atomic force microscopy oxidation lithography. InAs SCQDs directly grown on the patterned surface were used as a seed layer and strain template for the nucleation of optically active single InAs SCQDs. The preservation of the initial geometry of the engraved pattern motifs after the re-growth interface preparation process, the lack of buffer layer growth prior to InAs seed layer deposition and the development of suitable growth conditions provide us an improvement of the SCQDs’ active layer optical properties while retaining a high ratio of single occupation (89%). In this work a fivefold reduction of the average optical line-width from 870 μeV to 156 μeV for InAs SCQDs located 15 nm from the re-growth interface is obtained by increasing the temperature of the initial thermal treatment step of the re-growth interface from 490 °C to 530 °C. [ABSTRACT FROM AUTHOR]