InAs quantum dots array grown with an As2 source on non-planar GaAs substrates

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

“…Under these growth conditions it can be seen that dot nucleation on the restricted area on top of the ridge mesa has not led to a more uniform size distribution compared to the unpatterned area. This is similar to the photoluminescence measurements on QD chains on patterned substrates reported elsewhere [14,21,33,12,13,15]. It therefore appears that the forced alignment of dots in chains by substrate pre-patterning does not a priori result in improved dot uniformity.…”

“…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].…”

Electrical control of a laterally ordered InAs/InP quantum dash array

“…In the last years, quantum dot arrays or chains have been fabricated combining self-assembling methods with different patterning processes, 13,14,15,16,17 strain engineering of the substrate, 18,19 inclusion of misfit dislocations, 20,21 or cleaved edge overgrowth processes 22 . The optical quality of these QDs has been assessed by characterization of their ensemble photoluminescence, and increasing efforts are being directed to investigate the properties of individual QDs in the array 17,22 or to control them by applying a lateral electric field. 23 In the following, we present a new method to fabricate an array of elongated quantum dots or quantum dashes (QDh) based on the post-growth processing of a sample containing a single layer of self-assembled quantum wires (QWRs).…”

“…However, the fabrication of large, optically active, quantum dot arrays still remains a challenging task. In recent years, quantum dot arrays or chains have been fabricated combining self-assembling methods with different patterning processes [13][14][15][16][17], strain engineering of the substrate [18,19], inclusion of misfit dislocations [20,21], or cleaved edge overgrowth processes [22]. The optical quality of these QDs has been assessed by characterization of their ensemble photoluminescence, and increasing efforts are being directed to investigate the properties of individual QDs in the array [17,22] or to control them by applying a lateral electric field [23].…”