Incorporation of Sb and As in MBE grown GaAsxSb1−x layers

Abstract

With the increasing interest in low effective mass materials for intersubband devices, mixed As-Sb compounds, like GaAsxSb1−x or AlxIn1−xAsySb1−y, gain more and more attention. The growth of these materials, however, still provides significant challenges due to the complex interaction between As and Sb. In this work, we provide an in-depth study on the incorporation of Sb into the GaAsxSb1−x layers and compare our findings to the present literature on this topic. It is found that both the composition and the crystal quality of GaAsxSb1−x layers are strongly influenced by the growth rate due to the As-for-Sb exchange reaction which takes place at the growing surface, and that high crystal quality can be achieved when the growth is performed under Sb limited conditions.

Sb‐Mediated Tuning of Growth‐ and Exciton Dynamics in Entirely Catalyst‐Free GaAsSb Nanowires

“…[ 33,34 ] In dynamic equilibrium, this Sb‐rich surface layer promotes an As exchange reaction in existing Ga‐Sb bonds and thereby inhibits incorporation of Sb atoms, especially for high critical Sb surface coverages. [ 34,35 ] The presence versus absence of such critical Sb segregation layer has intriguing consequences for many aspects in growth, as well as structural and compositional properties as we show below.…”

“…As argued before, on highly Sb‐enriched surfaces (anti‐surfactant regime), the incorporation of Sb competes strongly with the detrimental Sb‐As exchange reaction. [ 33–35 ] This exchange reaction is, in fact, highly dependent on growth rate, as observed in literature on planar GaAsSb thin films [ 33,35 ] —that is, when growth rate is slow, the exchange of Sb and As adatoms has much more time to proceed, consequently lowering Sb incorporation, as opposed to high growth rates. We observe exactly this behavior in our NW, which corroborates the existence of an Sb‐rich surface layer limiting the growth and compositional uniformity under excess Sb supply.…”

“…In contrast, for larger Sb supply a transition to a Sb-rich surface reconstruction with significant Sb surface coverage can be anticipated, based on observations in planar layers. [34,35,37] Under such Sb-enriched surface, both As and Ga adatoms rapidly exchange their overlayer site for a sub-surface site, which strongly inhibits their adatom diffusion, [38] limiting axial growth. Below, we illustrate the effects of Sb-mediated adatom diffusion behavior in a more comprehensive way.…”

Evaluation of Material Systems for THz Quantum Cascade Laser Active Regions

“…These reactions at the growth surface can be suppressed by lowering the substrate temperature below 430 °C . For the growth of GaAs 1‐x Sb x , the crystal quality can furthermore be improved by using higher Ga fluxes, but at the cost of accuracy regarding the layer thicknesses, as discussed in section 4.…”

2.7 μ m quantum cascade detector: Above band gap energy intersubband detection

“…Lattice-matched AlAsSb layers were achieved by initially growing bulk AlAs 0.16 Sb 0.84 layers on InAs substrates. 22 Lattice-matched layers drastically decrease stress inside the material, reducing the probability of generating defects, and thicker structures can be grown. This is in contrast to GaSb substrates, which would be transparent for the absorption wavelength of the presented QCD and would therefore allow illumination through the substrate enabling more wave guiding options, but the InAs/AlAsSb heterostructure on GaSb would be needed to be grown strain-balanced because latticematched growth is impossible.…”