Structure and Electronic Properties of InSb Nanowires Grown in Flexible Polycarbonate Membranes.

Abhay Pratap Singh,Zaina Algarni,Teresa D Golden,Kevin Roccapriore,Riyadh Salloom,U Philipose

doi:10.3390/nano9091260

Abstract

A dense array of vertically aligned indium antimonide (InSb) nanowires with high aspect ratio (diameter 150 nm, length 20 m) were grown in the pores of a track-etched polycarbonate membrane via a one-step electrochemical method. There are several reports on InSb nanowire growth in the pores of a mechanically rigid, nano-channel alumina template (NCA), where nanowire growth occurs in the pores of the NCA. This work on InSb nanowire growth in pores of track-etched polycarbonate (PC) membrane sheds light on the various factors that affect nucleation and nanowire growth. The average length and diameter of the as-grown nanowires was about 10 m and 150 nm, respectively. Two possible mechanisms accounting for two different morphologies of the as-grown nanowires are proposed. The polycrystallinity observed in some of the nanowires is explained using the 3D ‘nucleation-coalescence’ mechanism. On the other hand, single crystal nanowires with a high density of twin defects and stacking faults grow epitaxially by a two-dimensional (2D) nucleation/growth mechanism. To assess the electrical quality of the nanowires, two- and four-terminal devices were fabricated using a single InSb nanowire contacted by two Ni electrodes. It was found that, at low bias, the ohmic current is controlled by charge diffusion from the bulk contacts. On the other hand, at high bias, the effects of space charge limited current (SCLC) are evident in the current–voltage behavior, characteristic of transport through structures with reduced electrostatic screening. A cross-over from ohmic to SCLC occurs at about 0.14 V, yielding a free carrier concentration of the order of cm.

Highlights

One-dimensional nanowires exhibit novel physical, optical and electronic properties, making them attractive for applications as interconnects and as nanoscale electronic, optoelectronic devices
We study the efficacy of using track-etched polycarbonate (PC) membranes as a template for InSb nanowire growth
We present our findings on the synthesis and characterization results of InSb nanowires that are electrochemically grown in template pores and we present a model explaining the role of electrodeposition parameters on the sample crystallinity

Summary

Introduction

One-dimensional nanowires exhibit novel physical, optical and electronic properties, making them attractive for applications as interconnects and as nanoscale electronic, optoelectronic devices. There are several nanowire growth techniques including high temperature growth by chemical vapor deposition (CVD) [20] and high-vacuum growth by molecular beam epitaxy (MBE) [21] In these cases, ordered growth of dense nanowire arrays requires patterning of the substrate with seed layers, the entire process requiring very sensitive control of the growth environment, resulting in a complex, expensive and non-scalable nanowire growth technique. An extremely successful approach for growing ordered arrays of nanowires with a high aspect ratio is electrochemical growth in non-conducting porous membranes This relatively inexpensive and versatile growth can be performed at room temperature, and is preferred for growth of compound semiconductors like InSb where the difference in vapor pressures between In and Sb can result in non-stoichiometric growth at high temperatures. The first challenge is to determine an appropriate template, with the required geometry in terms of pore diameter, channel length and surface chemistry that will facilitate total removal of template after nanowire growth without compromising the surface or composition of the nanowires

Methods

Results

Conclusion