Understanding the Thermodynamics of Si and Ge Concentration Variation in SiGeSn Nanowires

Abstract

This work presents a comprehensive investigation into the synthesis, characterization, and thermal stability of SiGeSn nanowires (NWs) leveraging the vapor–liquid–solid growth mechanism. Utilizing plasma‐enhanced chemical vapor deposition with Sn as the catalyst and a combination of SiH4 and GeH4 as precursors, this research synthesizes tapered SiGeSn NWs of high crystalline quality. Utilizing high‐angle annular dark‐field scanning transmission electron microscopy and energy‐dispersive X‐ray spectroscopy, the study confirms the inhomogeneous distribution of Si, Ge, and Sn along the NWs’ growth axis. It is observed that the concentrations of Si and Ge are significantly influenced by the NW diameter, a phenomenon attributed to the Gibbs–Thomson effect. A straightforward mathematical model is developed. This model examines the impact of the catalyst's shape and the presence of Sn on the NW surface on the internal Sn concentration and its variation along the NWs’ growth axis. Additionally, the study investigates how thermal annealing at temperatures of 300 and 600 °C induces compositional changes within the NWs. These changes are markedly influenced by the heterogeneous distribution of Si, Ge, and Sn elements, leading to varying levels of compositional alterations in different segments of the NWs postannealing at distinct temperatures.