Controlling nanowire growth through electric field-induced deformation of the catalyst droplet.

Federico Panciera,Frances M Ross,Sardar B Alam,Kristian Mølhave,Michael M Norton,Stephan Hofmann

doi:10.1038/ncomms12271

Abstract

Semiconductor nanowires with precisely controlled structure, and hence well-defined electronic and optical properties, can be grown by self-assembly using the vapour–liquid–solid process. The structure and chemical composition of the growing nanowire is typically determined by global parameters such as source gas pressure, gas composition and growth temperature. Here we describe a more local approach to the control of nanowire structure. We apply an electric field during growth to control nanowire diameter and growth direction. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet. This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and also to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth.

Highlights

Semiconductor nanowires with precisely controlled structure, and well-defined electronic and optical properties, can be grown by self-assembly using the vapour–liquid–solid process
We suggest that this deviation from spherical geometry is generated by the faceted nature of the nanowire on which the droplet sits
To develop applications of electric field-directed nanowire growth, it is important to apply the technique within conventional growth reactors

Summary

Introduction

Semiconductor nanowires with precisely controlled structure, and well-defined electronic and optical properties, can be grown by self-assembly using the vapour–liquid–solid process. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth. The chemical composition, diameter, growth direction and even crystal structure of the growing nanowire are modulated by changes in the basic growth parameters of temperature, and source gas pressure and composition[5,6,7,8,9,10,11]. VLS growth in an electric field in principle allows new opportunities for modulating growth and access to part of the parameter space that is otherwise unavailable, and can be a powerful tool for nanostructure control

Methods

Results

Conclusion