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(Color online) Surface morphology [two dimensional and three dimensional (3d)] by AFM and corresponding line profiles indicated as black lines in Figs. (a-1), (b-1), and (c-1). The InAs monolayer coverage is varied: (a) 0.0 ML, (b) 0.8 ML, and (c) 1.4 ML deposition at after 3 ML of Ga deposition at (equivalent amount of GaAs when was supplied) and crystallization at . Figures (a-1), (b-1), and (c-1) are , and Figs. (a-2), (b-2), and (c-2) are (enlarged 3D) . Black lines in the figures correspond to the line profiles shown in Figs. (a-3), (b-3), and (c-3).
(Color online) AFM images of (a) 1.6 ML, (b) 2.0 ML, and (c) 2.4 ML of InAs deposition at . InAs QDs were deposited after 3 ML of Ga deposition at (equivalent amount of GaAs when was supplied) and crystallization at . Inserted enlarged 3D AFM images are the major structures (most dominant structures) for the given sample. Figures are , and insertions are .
(Color online) Evolution of the QDMs from the GaAs mounds to the structures: (a) GaAs mound, (b) InAs shoulder, (c) bi-, (d) tri-, (e) quad-, (f) penta-, (g) hexa-molecules, and (h) a large hexa-QDM, and (i) a molecule with elongated nanostructures. All figures are , and the crystallographic direction in (a) and the scale bar in (c) are applied to the other images. InAs monolayer coverages associated with the acquisition of sample figures were as follows: (a) 0 ML, (b) 0.8 ML, (c) 1.4 ML, [(d) and (e)] 1.6 ML, [(f) and (g)] 2.0 ML, and [(h) and (i)] 2.4 ML.
PL spectra of InGaAs QDMs formed around nanoscale GaAs mound templates with 1.6 ML of InAs deposition at . The surface morphology is shown in Fig. 2(a). Six spectra peaks cover the range of laser power densities from , where is . The vertical arrows indicate the evolution of the PL peak from the ground state to the first and the second excited states .
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