Understanding the anisotropic growth of VS grown PbSnTe nanowires

TL;DR

This paper investigates the anisotropic growth mechanisms of PbSnTe nanowires grown via molecular beam epitaxy, developing a model that explains morphological evolution and guides improved nanowire device fabrication.

Contribution

It introduces a comprehensive growth model for PbSnTe nanowires that accounts for anisotropic effects and growth regime transitions, enhancing understanding of their morphology.

Findings

Growth morphology depends on growth time and transition from Te-limited to group IV-limited regimes.

Growth anisotropy is explained by a combination of impingement, mask diffusion, and facet diffusion.

The model enables targeted experiments for better nanowire device design.

Abstract

PbSnTe is a topological crystalline insulator (TCI), which holds promise for scattering-free transport channels and fault-tolerant quantum computing. As the topologically non-trivial states live on the surface, the nanowire geometry, with a high surface-to-volume ratio, is ideal for probing these states. The controlled growth of PbSnTe nanowires using molecular beam epitaxy has been shown before, but an understanding of the anisotropic growth and the resulting morphology is lacking. Here, based on experimental observations, we develop a model that describes the evolution of NW morphology as a function of growth time. It is found that the anisotropic morphology can be described by a combination of direct impingement, mask diffusion and facet diffusion which results in a transition from a Te-limited growth regime to a group IV-limited growth regime. This growth model allows us to design more targeted experiments which could lead to a higher flexibility in device design.