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(a) PVTEM image showing the distribution of QDs. (b) Cross-sectional HAADF-STEM images of two QDs.
(Color) Ga, In, As, and Sb elemental maps obtained from the analysis of the low-loss energy region of the spatially resolved background subtracted EEL spectra acquired from the same QD. Rainbow color code is used with red and violet colors representing the minimum and maximum concentrations, respectively. Ga and As maps were determined taking GaAs as a reference for 100% of both elements. In and Sb maps were determined as 100 minus the Ga and As maps, respectively. Concentrations of Ga and As in the range [, 100] are shown in violet, while concentrations of In and Sb in the range [0, ] are shown in red. is the standard deviation of the concentration for the element (Ga or As) measured from a region consisting of pure GaAs. and are assumed to be equal to (4.1%) and (5.1%), respectively. Maximum concentrations of Sb and In (violet color) are 41.1% and 43.9%, respectively.
(a) High resolution HAADF-STEM image of a QD. The approximate location of interfaces with the GaAs substrate and the GaAs capping layer are indicated on the image with dotted lines. The inset at the upper right corner shows the projected atomic structure. (b) Intensity profile taken along  across the central part of the HAADF-STEM image of (a).
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