Influence of the growth conditions on the ridge morphology during GaAs deposition on GaAs (001) patterned substrates

Abstract

Ridge structure transformation by group-III species modification during the growth of (Al,Ga)As on patterned substrates J. Appl. Phys. 97, 044905 (2005); 10.1063/1.1849433Planar InAs growth on GaAs(001) and subsequent quantum dot formation by a surface induced morphological instability J.The formation of ridge structures on ͗100͘ aligned mesa stripes defined on GaAs ͑001͒ substrates has been investigated as a function of the substrate temperature, V/III flux ratio, and GaAs deposition quantity. Across the entire range of deposition conditions employed, the ridge structures were observed to form with ͕110͖ facets, indicating a similar growth mechanism in all cases. The ͕110͖ facet lengths on the ridge structures were accurately reproduced using a simple one-dimensional geometric model that included the effects of Ga adatom migration from the ͕110͖ facets to the upper ridge surface and resulting in an additional Ga flux. The results have important implications for the controlled growth of micron-scale ridge structures on patterned substrates.

Growth of Single-Crystalline Wurtzite Aluminum Nitride Nanotips with a Self-Selective Apex Angle

“…A similar basis for the facet formation in a GaAs ridge morphology has recently been reported. [43] The (221) planes can be H or N terminated, depending on the bond enthalpies of Al±H and Al±N, where the former is smaller. The rapid etching rate on the N-terminated surface may lead to dangling-bond passivation by H, which is formed by decomposition of the ammonia gas at 950 C. However, at such high reaction temperatures, the stability of Al±H is questionable.…”

A comparison between GaAs and AlAs deposition on patterned substrates

“…Fig. 1 also demonstrates the difference for GaAs and AlAs, in the so-called swimming pool effect (SPE) [7,8] typically observed for growth on patterned substrates. The SPE is effectively a measure of the size of the region that appears as an inclined plane sloping from the top of the {1 1 0} facets, to the flat central (0 0 1) section on the ridge tops.…”

“…The preand post-growth mesa and ridge quality were assessed, ex situ by scanning electron microscopy (SEM) and atomic force microscopy. Careful sample preparation prior to growth, including both ex situ oxygen ashing and in situ atomic hydrogen cleaning procedures was found to be critical to the quality of the re-growth process [7,8,20]. After transfer to the deposition chamber, the patterned substrates were heated to approximately 620 1C, under an As 4 flux, to ensure both an oxide-free surface and a sharp (2 Â 4) RHEED pattern prior to adjustment of the sample temperature to that required for GaAs, AlAs or multilayer deposition.…”

“…The use of various diffusion length adspecies leads to additional complexity in the growth processes, since ridge formation utilises inter-planar adatom migration to attain the familiar peaked geometry. For example, during GaAs deposition, Ga adatoms are able to diffuse from less favoured planes to more kinetically preferred areas of the sample, for example, from the {1 1 0} facets to the (0 0 1) ridge top for /1 0 0S directed mesa stripes under standard GaAs deposition conditions, leading to enhanced film thickness in these areas [8]. This paper highlights the differences between GaAs and AlAs deposition and then expands these concepts to include the growth of multilayer AlAs/GaAs structures.…”

“…Deposition of III-V semiconductors on patterned substrates has been widely investigated [1][2][3][4][5] with the majority of studies concentrating on the growth of GaAs ridges on mesa structures [4,[6][7][8][9]. Heteroepitaxial growth on patterned GaAs substrates has received very little attention, however, especially with respect to AlAs deposition, apart from the use of thin Al(Ga)As marker layers for following the growth front development [6,10,11] and the formation of Al-containing quantum wires [12][13][14][15].…”