Growth of Self-Catalyzed InAs/InSb Axial Heterostructured Nanowires: Experiment and Theory.

Omer Arif,Fabio Beltram,Francesca Rossi,Vladimir G Dubrovskii,Valentina Zannier,Igor V Shtrom,Lucia Sorba

doi:10.3390/nano10030494

Abstract

The growth mechanisms of self-catalyzed InAs/InSb axial nanowire heterostructures are thoroughly investigated as a function of the In and Sb line pressures and growth time. Some interesting phenomena are observed and analyzed. In particular, the presence of In droplet on top of InSb segment is shown to be essential for forming axial heterostructures in the self-catalyzed vapor-liquid-solid mode. Axial versus radial growth rates of InSb segment are investigated under different growth conditions and described within a dedicated model containing no free parameters. It is shown that widening of InSb segment with respect to InAs stem is controlled by the vapor-solid growth on the nanowire sidewalls rather than by the droplet swelling. The In droplet can even shrink smaller than the nanowire facet under Sb-rich conditions. These results shed more light on the growth mechanisms of self-catalyzed heterostructures and give clear route for engineering the morphology of InAs/InSb axial nanowire heterostructures for different applications.

Highlights

InSb has the smallest band gap, the highest electron mobility and the largest thermo-power figure of merit among the entire family of III-V semiconductor compounds [1,2], which makes this material ideal for various applications in high speed electronics and photonics
Imaging was performed in high resolution (HR) transmission electron microscopy (TEM) mode combined with zero-loss energy filtering
We did not find any Sb signal around the InAs stem and the InAs/InSb axial

Summary

Introduction

InSb has the smallest band gap, the highest electron mobility and the largest thermo-power figure of merit among the entire family of III-V semiconductor compounds [1,2], which makes this material ideal for various applications in high speed electronics and photonics. There have been many efforts to grow InSb in the form of nanowires (NWs) on both on InSb substrates [5] and on lattice-mismatched substrates such as Si and InAs [6,7,8,9,10,11,12,13], which enables a radical improvement of its crystalline quality and may pave new ways to fabricate InSb-based devices Despite this progress, it is admittedly challenging to maintain the necessary control over the morphology and dimensions of InSb NWs, and many fundamental aspects of their growth and related properties are not yet fully understood. This understanding allows for the realization of Au-free and CMOS-compatible InAs/InSb heterostructured nanostructures with well controlled properties

Methods

Results

Conclusion