Selective formation and alignment of InAs quantum dots over mesa stripes along the [011] and [001] directions on GaAs (100) substrates

Abstract

We have studied the selective formation of InAs self-organized quantum dots on top of [001]- and [011]-oriented mesa stripes on patterned GaAs (100) substrates. The GaAs stripes are also grown by selective area epitaxy. The dot density and spatial distribution depend on both the stripe orientation and the width of the (100) top facet of the stripe. The density is higher for stripes aligned in the [001] direction, and lower for those aligned in the [011] direction, respectively, when compared to that obtained on a planar substrate under the same growth conditions. In addition, the dot uniformity is improved by reducing the top facet width below 200 nm in the growth of the mesa stripes, and well-aligned rows of dots are obtained for sub-100-nm widths.

Effect of GaAs polycrystal on the size and areal density of InAs quantum dots in selective area molecular beam epitaxy

“…The increase of QD areal density is a result of the high availability of atomic steps due to surface morphology in this region, especially in the area around the ends of mask stripes where the shallow non-planar epitaxial surfaces ($41 from the surface orientation far from the ridges, observed under cross-sectional SEM in the orientation B to B 0 ) between mask stripes join the flat surface outside the mask pattern and form multiple facets. It can also be seen that QDs self-align along the [1 1 0], [1 0 0], [0 1 0] edges of the epitaxial layers in agreement with previous observations [15][16][17]. This alignment of QDs is maintained along the whole length of the epitaxial mesa.…”

Si Based Nanostructure Growth Subsystem with Atomic Scale Control. Supersonic Molecular Beam Array Cell

“…Perfectly aligned and regularly spaced one-dimensional array of the Ge dots was formed on the ridge of the Si stripe mesa. Similar result was reported by other groups [25,26]. The perfect alignment of the dots along the Si stripe mesas is attributed to selfregulation mechanism driven by the minimization of the total energy, and also assisted by the formation of the ridges [27].…”

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

“…The dot size is about 25 nm in diameter. To fabricate the QD arrays on the non-planar substrate, reducing the ridge top width below 100 nm was needed using chemical beam epitaxy [2]. The well-aligned QD arrays can be grown easily on the 300 nm GaAs ridges by using the As 2 source in MBE.…”

“…To realize such quantum devices, it is important to control the position and the size distribution of the QDs. Selective growth on non-planar substrates has been utilized to control the position of QD arrays [1][2][3]. An improvement in InAs QDs uniformity and well-aligned QD arrays have already been achieved by reducing the top facet width below 200 and 100 nm, respectively [2].…”