Anisotropic Confinement, Electronic Coupling and Strain Induced Effects Detected by Valence-Band Anisotropy in Self-Assembled Quantum Dots

Abstract

A method to determine the effects of the geometry and lateral ordering on the electronic properties of an array of one-dimensional self-assembled quantum dots is discussed. A model that takes into account the valence-band anisotropic effective masses and strain effects must be used to describe the behavior of the photoluminescence emission, proposed as a clean tool for the characterization of dot anisotropy and/or inter-dot coupling. Under special growth conditions, such as substrate temperature and Arsenic background, 1D chains of In0.4Ga0.6 As quantum dots were grown by molecular beam epitaxy. Grazing-incidence X-ray diffraction measurements directly evidence the strong strain anisotropy due to the formation of quantum dot chains, probed by polarization-resolved low-temperature photoluminescence. The results are in fair good agreement with the proposed model.

Structural and magnetic confinement of holes in the spin-polarized emission of coupled quantum ring–quantum dot chains

“…1(c). The details of the transformation on valence band due to the combination of strain profiles, spatial and magnetic confinements, as well as interdot coupling are given in a number of reported studies [27][28][29]. The magnetic tuning of the valence band character (HH or LH) in QDs has already been reported experimentally and confirmed theoretically [30,31].…”

In-plane mapping of buried InGaAs quantum rings and hybridization effects on the electronic structure

“…In such iso-strain projections, the areas with each lattice parameter are drawn following the simple ellipse constraint ðx 2 =L 2 ½110 Þ þ ðy 2 =L 2 ½1 10 Þ 1, where x, y and L ½110 , L ½1 10 are the coordinates and iso-lattice lateral size parameters along the [110] and ½1 10 directions. 30 In Figs. 5(a) and 5(b), we show the in-plane iso-lattice parameter ða == Þ projections for dots and rings, as obtained from the size evaluation of Figs.…”

“…Similar profiles for the longitudinal scans were found at the (220) and ð2 20Þ reflections, thus initially suggesting the absence of strain anisotropy in both systems. 30 The location of regions with iso-lattice parameter-also used for the further composition analysis depicted in the following paragraphs-can be evaluated by the interpretation of transversal scans, shown in Fig. 4(b).…”

“…The iso-lattice parameter profile of QR shows, therefore, an elongation in the ½1 10 direction. 30 The signature of such size anisotropy being clearer in the transversal scans than in the longitudinal scans may be ascribed to the highly strained condition in which buried rings are subjected.…”

Resonant X-ray diffraction of self-assembled epitaxial systems: From direct to complementary chemical information

“…4(b) can be employed to draw a twodimensional projection map of in-plane local lattice parameter a = a SnTe h/2 (considering |h| = |k|) -for EuTe islands. In such iso-strain projections the areas with each lattice parameter are drawn following the simple ellipse constraint (x 2 + y 2 /L 2 ) ≤ 1, where x,y and L are the coordinates and iso-lattice parameter lateral size along the [1][2][3][4][5][6][7][8][9][10] and [2,11] directions, here considered the same accordingly to the equal L sizes obtained from measurements in the 220 family of reflections [23]. Figure 4(c) shows the in-plane iso-lattice parameter projections for dots.…”