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See detailSize- and shape-dependent phase diagram of In–Sb nano-alloys
Ghasemi, Masoomeh; Zanolli, Zeila ULg; Stankovski, Martin et al

in Nanoscale (2015), 7

Nano-scale alloy systems with at least one dimension below 100 nm have different phase stabilities than those observed in the macro-scale systems due to a large surface to volume ratio. We have used the ... [more ▼]

Nano-scale alloy systems with at least one dimension below 100 nm have different phase stabilities than those observed in the macro-scale systems due to a large surface to volume ratio. We have used the semi-empirical thermodynamic modelling, i.e. the CALPHAD method, to predict the phase equilibria of the In–Sb nano-scale systems as a function of size and shape. To calculate the size- and shape-depen- dent phase diagram of the In–Sb system, we have added size-dependent surface energy terms to the Gibbs energy expressions in the In–Sb thermodynamic database. We estimated the surface energies of the solution phases and of the InSb intermetallic phase using the Butler equation and DFT calculations, respectively. A melting point and eutectic point depression were observed for both nanoparticle and nanowire systems. The eutectic composition on the In-rich and Sb-rich sides of the phase diagram shifted towards higher solubility. We believe that the phase diagram of In–Sb nano-alloys is useful for an increased understanding of the growth parameters and mechanisms of InSb nanostructures. [less ▲]

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See detailGrowth of Straight InAs-on-GaAs Nanowire Heterostructures
Messing, Maria E; Wong-Leung, Jennifer; Zanolli, Zeila ULg et al

in Nano Letters (2011), 11(9), 3899-3905

One of the main motivations for the great interest in semiconductor nanowires is the possibility of easily growing advanced heterostructures that might be difficult or even impossible to achieve in thin ... [more ▼]

One of the main motivations for the great interest in semiconductor nanowires is the possibility of easily growing advanced heterostructures that might be difficult or even impossible to achieve in thin films. For III␣V semiconductor nanowires, axial heterostructures with an interchange of the group III element typically grow straight in only one interface direction. In the case of InAs␣GaAs heterostructures, straight nanowire growth has been demonstrated for growth of GaAs on top of InAs, but so far never in the other direction. In this article, we demonstrate the growth of straight axial heterostructures of InAs on top of GaAs. The heterostructure interface is sharp and we observe a dependence on growth parameters closely related to crystal structure as well as a diameter dependence on straight nanowire growth. The results are discussed by means of accurate first principles calculations of the inter- facial energies. In addition, the role of the gold seed particle, the effect of its composition at different stages during growth, and its size are discussed in relation to the results observed. [less ▲]

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