An Overview of Modeling Approaches for Compositional Control in III-V Ternary Nanowires

Modeling of the growth process is required for the synthesis of III-V ternary nanowires with controllable composition. Consequently, new theoretical approaches for the description of epitaxial growth and the related chemical composition of III-V ternary nanowires based on group III or group V intermix were recently developed. In this review, we present and discuss existing modeling strategies for the stationary compositions of III-V ternary nanowires and try to systematize and link them in a general perspective. In particular, we divide the existing approaches into models that focus on the liquid-solid incorporation mechanisms in vapor-liquid-solid nanowires (equilibrium, nucleation-limited, and kinetic models treating the growth of solid from liquid) and models that provide the vapor-solid distributions (empirical, transport-limited, reaction-limited, and kinetic models treating the growth of solid from vapor). We describe the basic ideas underlying the existing models and analyze the similarities and differences between them, as well as the limitations and key factors influencing the stationary compositions of III-V nanowires versus the growth method. Overall, this review provides a basis for choosing a modeling approach that is most appropriate for a particular material system and epitaxy technique and that underlines the achieved level of the compositional modeling of III-V ternary nanowires and the remaining gaps that require further studies.

Kinetic modeling of interfacial abruptness in axial nanowire heterostructures

Kinetic modeling of the formation of axial III-V nanowire heterostructures grown by the Au-catalyzed vapor-liquid-solid method is presented. The method is based on a combination of kinetic growth theory for different binaries at the liquid-solid interface and thermodynamics of ternary liquid and solid alloys. Non-stationary treatment of the compositional change obtained by swapping material fluxes allows us to compute the interfacial abruptness across nanowire heterostructures and leads to the following results. At high enough supersaturation in liquid, there is no segregation of dissimilar binaries in solid even for materials with strong interactions between III and V pairs, such as InGaAs. This leads to the suppression of the miscibility gaps by kinetic factors. Increasing the Au concentration widens the heterointerface at low Au content and narrows it at high Au content in a catalyst droplet. The model fits quite well the data on the compositional profiles across nanowire heterostructures based on both group III and group V interchange. Very sharp heterointerfaces in double of InAs/InP/InAs nanowire heterostructures is explained by a reduced reservoir effect due to low solubility of group V elements in liquid.

Texturing Crystal Plane of Zinc Metal via Cleavage Fracture for a Dendrite-Free Zinc Anode

The dendrite problem of zinc anodes leads to poor cyclic life and safety hazards, which seriously hinders the development of aqueous zinc-ion batteries (ZIBs). Herein, we propose a new strategy to develop textured zinc anodes with preferential orientation (002) by cleavage fracture along the interface of zinc foil and low lattice mismatched CuZn5 alloy, which is highly reversible, long-life, and dendrite-free. The sequentially distributed (002) cleavage texture has high surface energy and strong binding energy with zinc atoms, which can significantly reduce the nucleation barrier of zinc and facilitate uniform zinc deposition. Furthermore, the cleavage texture of (002) planes promotes the epitaxial growth of zinc and prevents the dendrite formation. As a result, the zinc anode with the (002) cleavage plane (ZCP(002)) possesses an ultralong lifetime of about 2500 h in 1 mA cm-2 and 1 mA h cm-2 of symmetric battery and a high average Coulombic efficiency (99.7%) over 925 cycles in ZCP(002)|Cu asymmetric cells. This work provides new insights into modifying metal anodes from the perspective of crystallographic orientation and optimizing zinc anodes for the large-scale application of ZIBs.

Interfacial profile of axial nanowire heterostructures in the nucleation limited regime

We report thermodynamic modeling of the formation of axial III–V nanowire heterostructures grown by the self-catalyzed and Au-catalyzed vapor–liquid–solid methods.