Distribution of self-assembled InAs dots on patterned GaAs (100) substrates

The growth of GaAs and InAs dots on etched mesas: The effect of substrate temperature on mesa profile and surface morphology on dot distribution

“…Such ordering of InAs dots on the top of GaAs ridges has been previously observed on ridge mesas with (111)B (541) sidewalls, (4 11)A (191) sidewalls [26] and (11 0) (451) sidewalls [7], and here with (5 3 3)B (401) sidewalls-implying that this method of aligning dots is relatively insensitive to the mesa shape provided deep (o500 nm) patterned mesas are used. This should be contrasted with the case for shallower patterns, ($25 nm deep), where an InGaAs stressor layer is required to increase the strainrelaxation contribution to the chemical potential to ensure dot formation at mesa tops [8,10].…”

“…4a is a plan view AFM image of the top, 900 nm wide, (1 0 0) plane of a mesa from Sample A. There is a very low density of InAs dots in the central 0.25 Â 1.00 mm 2 region (shown by the dashed rectangular area in the image) with a higher density of InAs dots nucleated along the mesa edge, as previously reported on mesas with different sidewalls [7,26].…”

Fabrication of a self-aligned cross-wire quantum-dot chain light emitting diode by molecular beam epitaxial regrowth

“…Alternatively, QD chains can form on the top of ridge mesas. This is due to net migration from sidewalls to the mesa top, together with the relaxation of strain energy possible on convex-curved surfaces [16][17][18][19][20][21][22][23]. Such ridge-shaped substrates have the added advantage that they can significantly enhance the luminescence extraction efficiency compared to planar substrates [24].…”

“…These ridge mesas can be formed by pre-patterning the surface with large mesas which subsequently narrow during buffer layer overgrowth due to surface faceting and subsequent net adatom migration between neighbouring facets [16,22,23,21], or by selective area epitaxy where ridge-shaped mesas grow in windows in an amorphous oxide surface mask layer [19,17]. The latter method has been the most successful method so far in fabricating single chains of dots of uniform size once the mesa top surface is less than 50 nm wide in the InAs/InP material system [19] and in InAs/GaAs structures grown by chemical beam epitaxy [17]; however, it is less successfully applied to solid source InAs/GaAs MBE growth due to the high sticking coefficient of GaAs onto the mask material at conventional growth temperatures [25,26].…”

Location of quantum dots identified by microscopic photoluminescence changes during nanoprobe indentation with a horizontal scan

“…This involves knowledge on three fronts: location of the QD, strain experienced by the QD, and response of the QD. For the location of the QD, various methods had been employed to describe the conformation of the QD sample, such as scanning electron microscope, 11,12 scanning tunneling microscope, 13,14 atomic force microscope, 11,12 and surface-sensitive grazing incidence x-ray diffraction. 15 For the strain-based modulation of the QD, much work has been done to tune the discrete energy levels of QDs by thermal annealing, 16 strain-release capping layer, 17 hydrostatic pressure by diamond-anvil cell, 18 and local indentation by nanoprobe.…”