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

Abstract

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.

Circumventing the Uncertainties of the Liquid Phase in the Compositional Control of VLS III–V Ternary Nanowires Based on Group V Intermix

“…Most III–V NWs are grown using different epitaxy techniques via the VLS method using a catalyst droplet, often Au [ 7 ], which can be replaced with a group III metal (Ga) in the self-catalyzed VLS approach [ 8 ]. The VLS growth of a ternary A x B 1−x C NW is a complex process whereby the vapor phase containing A, B and C species condenses in a quaternary liquid phase consisting of A, B, C and Au atoms (in the case of a Au catalyst) and then crystallizes into a ternary A x B 1−x C NW [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Due to the presence of a catalyst droplet, whose composition is generally unknown, the compositional control of VLS III–V ternary NWs remains a challenging task [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”

“…The VLS growth of a ternary A x B 1−x C NW is a complex process whereby the vapor phase containing A, B and C species condenses in a quaternary liquid phase consisting of A, B, C and Au atoms (in the case of a Au catalyst) and then crystallizes into a ternary A x B 1−x C NW [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Due to the presence of a catalyst droplet, whose composition is generally unknown, the compositional control of VLS III–V ternary NWs remains a challenging task [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Full understanding of the VLS growth of III–V ternary NWs, particularly those based on group V intermix, has not been achieved hitherto.…”

“…The key parameters and factors influencing the composition of III–V ternary NWs grown by the VLS method are introduced as follows [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The composition of a quaternary liquid in a catalyst droplet is described by three independent variables, for example, (i) the fraction of A atoms in liquid, where and are the atomic concentrations of A and B atoms in liquid; (ii) the total concentration of A and B atoms in liquid, ; and (iii) the concentration of C atoms in liquid , with .…”

“…The vapor phase, producing three atomic fluxes of A, B and C atoms , and , can be described by the fraction of A atoms in vapor, where the total flux of A and B atoms , and the flux ratio is . The liquid–solid distribution links the solid and liquid composition, whereas the vapor–solid distribution links the solid and vapor composition [ 10 , 12 ].…”

Chemical Vapor Deposition of Elemental Crystallogen Thin Films

“…As a matter of fact, the approach is accepted for the determination of vapor-solid distributions for III-V,. 154,155 And recently a few tweaks unleashed thermodynamics full potential on crystallogens,. 17 Carrier gas contribution is ignored, and species enthalpy of formation is not used in this report,.…”